    <SEC-DOCUMENT>0000937556-23-000156-index.html : 20230620
    <SEC-HEADER>0000937556-23-000156.hdr.sgml : 20230620
    <ACCEPTANCE-DATETIME>20230620090227
    ACCESSION NUMBER:		0000937556-23-000156
    CONFORMED SUBMISSION TYPE:	DEFA14A
    PUBLIC DOCUMENT COUNT:		7
    FILED AS OF DATE:		20230620
    DATE AS OF CHANGE:		20230620

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			MASIMO CORP
    		CENTRAL INDEX KEY:			0000937556
    		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
    		IRS NUMBER:				330368882
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		DEFA14A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-33642
    		FILM NUMBER:		231023664

    	BUSINESS ADDRESS:
    		STREET 1:		52 DISCOVERY
    		CITY:			IRVINE
    		STATE:			CA
    		ZIP:			92618
    		BUSINESS PHONE:		949-297-7000

    	MAIL ADDRESS:
    		STREET 1:		52 DISCOVERY
    		CITY:			IRVINE
    		STATE:			CA
    		ZIP:			92618
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>DEFA14A
    <SEQUENCE>1
    <FILENAME>masi-20230620axdefa14a.htm
    <DESCRIPTION>DEFA14A
    <TEXT>
    Document 1 - file: masi-20230620axdefa14a.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>2
    <FILENAME>masimologo300x1a05a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 2 - file: masimologo300x1a05a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>3
    <FILENAME>shareholderletterp1a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 3 - file: shareholderletterp1a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>shareholderletterp2a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 4 - file: shareholderletterp2a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>shareholderletterp3a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: shareholderletterp3a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>shareholderletterp4a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: shareholderletterp4a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>shareholderletterp5a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: shareholderletterp5a.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>