    <SEC-DOCUMENT>0001193125-24-215436-index.html : 20240909
    <SEC-HEADER>0001193125-24-215436.hdr.sgml : 20240909
    <ACCEPTANCE-DATETIME>20240909060634
    ACCESSION NUMBER:		0001193125-24-215436
    CONFORMED SUBMISSION TYPE:	S-1/A
    PUBLIC DOCUMENT COUNT:		27
    FILED AS OF DATE:		20240909
    DATE AS OF CHANGE:		20240909

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			MBX Biosciences, Inc.
    		CENTRAL INDEX KEY:			0001776111
    		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
    		ORGANIZATION NAME:           	03 Life Sciences
    		IRS NUMBER:				000000000
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		S-1/A
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-281764
    		FILM NUMBER:		241285721

    	BUSINESS ADDRESS:
    		STREET 1:		12406 HORESHAM STREET
    		CITY:			CARMEL
    		STATE:			IN
    		ZIP:			46032
    		BUSINESS PHONE:		3179893100

    	MAIL ADDRESS:
    		STREET 1:		12406 HORESHAM STREET
    		CITY:			CARMEL
    		STATE:			IN
    		ZIP:			46032
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>S-1/A
    <SEQUENCE>1
    <FILENAME>d790774ds1a.htm
    <DESCRIPTION>S-1/A
    <TEXT>
    Document 1 - file: d790774ds1a.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-1.1
    <SEQUENCE>2
    <FILENAME>d790774dex11.htm
    <DESCRIPTION>EX-1.1
    <TEXT>
    Document 2 - file: d790774dex11.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-3.1
    <SEQUENCE>3
    <FILENAME>d790774dex31.htm
    <DESCRIPTION>EX-3.1
    <TEXT>
    Document 3 - file: d790774dex31.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-5.1
    <SEQUENCE>4
    <FILENAME>d790774dex51.htm
    <DESCRIPTION>EX-5.1
    <TEXT>
    Document 4 - file: d790774dex51.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.7
    <SEQUENCE>5
    <FILENAME>d790774dex107.htm
    <DESCRIPTION>EX-10.7
    <TEXT>
    Document 5 - file: d790774dex107.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.1
    <SEQUENCE>6
    <FILENAME>d790774dex231.htm
    <DESCRIPTION>EX-23.1
    <TEXT>
    Document 6 - file: d790774dex231.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-FILING FEES
    <SEQUENCE>7
    <FILENAME>d790774dexfilingfees.htm
    <DESCRIPTION>EX-FILING FEES
    <TEXT>
    Document 7 - file: d790774dexfilingfees.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>g790774dsp01.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: g790774dsp01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>g790774g00a06.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: g790774g00a06.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>g790774g00m01.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: g790774g00m01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>g790774g00s44.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: g790774g00s44.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>g790774g02s97.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: g790774g02s97.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>g790774g14v41.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: g790774g14v41.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>g790774g40a82.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: g790774g40a82.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>g790774g43a01.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: g790774g43a01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>g790774g48m48.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 16 - file: g790774g48m48.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>g790774g59i17.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 17 - file: g790774g59i17.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>g790774g70y95.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 18 - file: g790774g70y95.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>g790774g72d51.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 19 - file: g790774g72d51.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>g790774g75h77.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 20 - file: g790774g75h77.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>21
    <FILENAME>g790774g75q33.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 21 - file: g790774g75q33.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>22
    <FILENAME>g790774g77b51.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 22 - file: g790774g77b51.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>23
    <FILENAME>g790774g80i17.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 23 - file: g790774g80i17.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>24
    <FILENAME>g790774g80w10.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 24 - file: g790774g80w10.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>25
    <FILENAME>g790774g82i98.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 25 - file: g790774g82i98.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>26
    <FILENAME>g790774g83a26.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 26 - file: g790774g83a26.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>27
    <FILENAME>g790774g84m86.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 27 - file: g790774g84m86.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>