    <SEC-DOCUMENT>0001193125-19-240403-index.html : 20190909
    <SEC-HEADER>0001193125-19-240403.hdr.sgml : 20190909
    <ACCEPTANCE-DATETIME>20190909060842
    ACCESSION NUMBER:		0001193125-19-240403
    CONFORMED SUBMISSION TYPE:	S-1/A
    PUBLIC DOCUMENT COUNT:		22
    FILED AS OF DATE:		20190909
    DATE AS OF CHANGE:		20190909

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			EXAGEN INC.
    		CENTRAL INDEX KEY:			0001274737
    		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-MEDICAL LABORATORIES [8071]
    		IRS NUMBER:				000000000
    		STATE OF INCORPORATION:			DE

    	FILING VALUES:
    		FORM TYPE:		S-1/A
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-233446
    		FILM NUMBER:		191080762

    	BUSINESS ADDRESS:
    		STREET 1:		1261 LIBERTY WAY
    		CITY:			VISTA
    		STATE:			CA
    		ZIP:			92081
    		BUSINESS PHONE:		(760) 560-1501

    	MAIL ADDRESS:
    		STREET 1:		1261 LIBERTY WAY
    		CITY:			VISTA
    		STATE:			CA
    		ZIP:			92081

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	EXAGEN DIAGNOSTICS INC
    		DATE OF NAME CHANGE:	20031230
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>S-1/A
    <SEQUENCE>1
    <FILENAME>d692844ds1a.htm
    <DESCRIPTION>S-1/A
    <TEXT>
    Document 1 - file: d692844ds1a.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-3.1
    <SEQUENCE>2
    <FILENAME>d692844dex31.htm
    <DESCRIPTION>EX-3.1
    <TEXT>
    Document 2 - file: d692844dex31.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-4.1
    <SEQUENCE>3
    <FILENAME>d692844dex41.htm
    <DESCRIPTION>EX-4.1
    <TEXT>
    Document 3 - file: d692844dex41.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-5.1
    <SEQUENCE>4
    <FILENAME>d692844dex51.htm
    <DESCRIPTION>EX-5.1
    <TEXT>
    Document 4 - file: d692844dex51.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.3
    <SEQUENCE>5
    <FILENAME>d692844dex103.htm
    <DESCRIPTION>EX-10.3
    <TEXT>
    Document 5 - file: d692844dex103.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.4
    <SEQUENCE>6
    <FILENAME>d692844dex104.htm
    <DESCRIPTION>EX-10.4
    <TEXT>
    Document 6 - file: d692844dex104.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.5
    <SEQUENCE>7
    <FILENAME>d692844dex105.htm
    <DESCRIPTION>EX-10.5
    <TEXT>
    Document 7 - file: d692844dex105.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.34
    <SEQUENCE>8
    <FILENAME>d692844dex1034.htm
    <DESCRIPTION>EX-10.34
    <TEXT>
    Document 8 - file: d692844dex1034.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.36
    <SEQUENCE>9
    <FILENAME>d692844dex1036.htm
    <DESCRIPTION>EX-10.36
    <TEXT>
    Document 9 - file: d692844dex1036.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.37
    <SEQUENCE>10
    <FILENAME>d692844dex1037.htm
    <DESCRIPTION>EX-10.37
    <TEXT>
    Document 10 - file: d692844dex1037.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.38
    <SEQUENCE>11
    <FILENAME>d692844dex1038.htm
    <DESCRIPTION>EX-10.38
    <TEXT>
    Document 11 - file: d692844dex1038.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.1
    <SEQUENCE>12
    <FILENAME>d692844dex231.htm
    <DESCRIPTION>EX-23.1
    <TEXT>
    Document 12 - file: d692844dex231.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>g692844dsp01.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: g692844dsp01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>g692844dsp02.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: g692844dsp02.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>g692844ex10_13pg001.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: g692844ex10_13pg001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>g692844ex10_13pg003.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 16 - file: g692844ex10_13pg003.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>g692844g12m29.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 17 - file: g692844g12m29.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>g692844g12z65.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 18 - file: g692844g12z65.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>g692844g50a84.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 19 - file: g692844g50a84.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>g692844g69j63.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 20 - file: g692844g69j63.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>21
    <FILENAME>g692844g70h03.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 21 - file: g692844g70h03.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>22
    <FILENAME>g692844g91e59.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 22 - file: g692844g91e59.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>