<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001856542</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0001447362</issuerCik>
            <issuerName>CASTLE BIOSCIENCES INC</issuerName>
            <secFileNumber>001-38984</secFileNumber>
            <issuerAddress>
                <ns2:street1>505 S. Friendswood Drive, Suite 401</ns2:street1>
                <ns2:city>Friendstown</ns2:city>
                <ns2:stateOrCountry>TX</ns2:stateOrCountry>
                <ns2:zipCode>77546</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>8667889007</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>TOBIN JUVENAL</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Officer</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>2230</noOfUnitsSold>
            <aggregateMarketValue>63800.30</aggregateMarketValue>
            <noOfUnitsOutstanding>28007301</noOfUnitsOutstanding>
            <approxSaleDate>01/06/2025</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>04/26/2022</acquiredDate>
            <natureOfAcquisitionTransaction>Acquisition of AltheaDx</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>2230</amountOfSecuritiesAcquired>
            <paymentDate>04/26/2022</paymentDate>
            <natureOfPayment>N/A</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>10b5-1 Sales for TOBIN JUVENAL</name>
                <address>
                    <ns2:street1>505 S. Friendswood Drive, Suite 401</ns2:street1>
                    <ns2:city>Friendstown</ns2:city>
                    <ns2:stateOrCountry>TX</ns2:stateOrCountry>
                    <ns2:zipCode>77546</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <saleDate>11/05/2024</saleDate>
            <amountOfSecuritiesSold>3507</amountOfSecuritiesSold>
            <grossProceeds>124692.79</grossProceeds>
        </securitiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>10b5-1 Sales for TOBIN JUVENAL</name>
                <address>
                    <ns2:street1>505 S. Friendswood Drive, Suite 401</ns2:street1>
                    <ns2:city>Friendstown</ns2:city>
                    <ns2:stateOrCountry>TX</ns2:stateOrCountry>
                    <ns2:zipCode>77546</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <saleDate>11/01/2024</saleDate>
            <amountOfSecuritiesSold>3100</amountOfSecuritiesSold>
            <grossProceeds>109707.02</grossProceeds>
        </securitiesSoldInPast3Months>
        <remarks>The securities to be sold were acquired upon the acquisition of AltheaDx during the period of 04/26/2022 through 12/05/2023.
</remarks>
        <noticeSignature>
            <noticeDate>01/06/2025</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>09/11/2024</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/ Tobin Juvenal</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
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144
0001856542
XXXXXXXX
LIVE
0001447362
CASTLE BIOSCIENCES INC
001-38984
505 S. Friendswood Drive, Suite 401
Friendstown
TX
77546
8667889007
TOBIN JUVENAL
Officer
Common
Morgan Stanley Smith Barney LLC Executive Financial Services
1 New York Plaza
8th Floor
New York
NY
10004
2230
63800.30
28007301
01/06/2025
NASDAQ
Common
04/26/2022
Acquisition of AltheaDx
Issuer
N
2230
04/26/2022
N/A
N
10b5-1 Sales for TOBIN JUVENAL
505 S. Friendswood Drive, Suite 401
Friendstown
TX
77546
Common
11/05/2024
3507
124692.79
10b5-1 Sales for TOBIN JUVENAL
505 S. Friendswood Drive, Suite 401
Friendstown
TX
77546
Common
11/01/2024
3100
109707.02
The securities to be sold were acquired upon the acquisition of AltheaDx during the period of 04/26/2022 through 12/05/2023.
01/06/2025
09/11/2024
/s/ Tobin Juvenal