<SEC-DOCUMENT>0001127602-18-006182.txt : 20180214
<SEC-HEADER>0001127602-18-006182.hdr.sgml : 20180214
<ACCEPTANCE-DATETIME>20180214183844
ACCESSION NUMBER:		0001127602-18-006182
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20180212
FILED AS OF DATE:		20180214
DATE AS OF CHANGE:		20180214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Vounatsos Michel
		CENTRAL INDEX KEY:			0001672709

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19311
		FILM NUMBER:		18615333

	MAIL ADDRESS:	
		STREET 1:		BIOGEN INC.
		STREET 2:		225 BINNEY ST.
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOGEN INC.
		CENTRAL INDEX KEY:			0000875045
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				330112644
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		225 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		7814642000

	MAIL ADDRESS:	
		STREET 1:		225 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOGEN IDEC INC.
		DATE OF NAME CHANGE:	20070427

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOGEN IDEC INC
		DATE OF NAME CHANGE:	20031112

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	IDEC PHARMACEUTICALS CORP / DE
		DATE OF NAME CHANGE:	19970530
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-02-12</periodOfReport>

    <issuer>
        <issuerCik>0000875045</issuerCik>
        <issuerName>BIOGEN INC.</issuerName>
        <issuerTradingSymbol>BIIB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001672709</rptOwnerCik>
            <rptOwnerName>Vounatsos Michel</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BIOGEN INC.</rptOwnerStreet1>
            <rptOwnerStreet2>225 BINNEY ST.</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <officerTitle>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2018-02-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>36320</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-02-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>36320</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>36320</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Suzanne Murray, Attorney in Fact for Michel Vounatsos</signatureName>
        <signatureDate>2018-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>doc1.txt
<DESCRIPTION>POWER OF ATTORNEY (PUBLIC): POWER OF ATTORNEY
<TEXT>
LIMITED POWER OF ATTORNEY FOR
SECTION 16 REPORTING OBLIGATIONS


	Know all by these presents, that the undersigned hereby makes,
constitutes and appoints Susan H. Alexander, James Basta, Marcia J. Gookin
and Suzanne Murray as the undersigned's true and lawful attorney-in-fact,
with full power and authority as hereinafter described on behalf of and in
the name, place and stead of the undersigned to:

(1)	prepare, execute in the undersigned?s name and on the undersigned?s
 behalf, and submit to the U.S. Securities and Exchange Commission
(the ?SEC?) a Form ID, including amendments thereto, and any other documents
necessary or appropriate to obtain codes and passwords enabling the
undersigned to make electronic filings with the SEC of reports required
by Section 16(a) of the Securities Exchange Act of 1934 and the rules and
regulations promulgated thereunder, as amended from time to time (the
"Exchange Act"), or any rule or regulation of the SEC;

(2)	prepare, execute, acknowledge, deliver and file Forms 3, 4,
and 5 (including any amendments thereto) with respect to the securities
of Biogen Inc., a Delaware corporation (the "Company"), with the SEC,
any national securities exchanges and the Company, as considered necessary
or advisable under Section 16(a) of the Exchange Act;

(3)	seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information on transactions in the Company's
securities from any third party, including brokers, employee benefit
plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to the undersigned and
approves and ratifies any such release of information; and

(4)	perform any and all other acts which in the discretion of such
attorney-in-fact are necessary or desirable for and on behalf of the
undersigned in connection with the foregoing.

The undersigned acknowledges that:

(A)	this Limited Power of Attorney authorizes, but does not require,
such attorney-in-fact to act in their discretion on information provided
to such attorney-in-fact without independent verification of such
information;

(B)	any documents prepared and/or executed by such attorney-in-fact
on behalf of the undersigned pursuant to this Limited Power of Attorney
will be in such form and will contain such information and disclosure
as such attorney-in-fact, in his or her discretion, deems necessary or
desirable;

(C)	neither the Company nor such attorney-in-fact assumes (i) any
liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned
for any failure to comply with such requirements, or (iii) any obligation
or liability of the undersigned for profit disgorgement under Section 16(b)
of the Exchange Act; and

(D)	this Limited Power of Attorney does not relieve the undersigned
from responsibility for compliance with the undersigned's obligations
under the Exchange Act, including without limitation the reporting
requirements under Section 16 of the Exchange Act.

	The undersigned hereby gives and grants the foregoing
attorney-in-fact full power and authority to do and perform all
and every act and thing whatsoever requisite, necessary or appropriate
to be done in and about the foregoing matters as fully to all intents
and purposes as the undersigned might or could do if present, hereby
ratifying all that such attorney-in-fact of, for and on behalf of
the undersigned, shall lawfully do or cause to be done by virtue of
this Limited Power of Attorney.

	This Limited Power of Attorney shall remain in full force
and effect until revoked by the undersigned in a signed writing
delivered to such attorney-in-fact.

	IN WITNESS WHEREOF, the undersigned has caused this Limited
Power of Attorney to be executed as of this 14th day of February, 2018.

                                        _/s/ Michel Vounatsos __
					Signature

					Name:  Michel Vounatsos
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
