<?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>0001998250</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0001990354</issuerCik>
            <issuerName>WAYSTAR HOLDING CORP</issuerName>
            <secFileNumber>001-42125</secFileNumber>
            <issuerAddress>
                <ns2:street1>1550 Digital Drive, #300</ns2:street1>
                <ns2:city>Lehi</ns2:city>
                <ns2:stateOrCountry>UT</ns2:stateOrCountry>
                <ns2:zipCode>84043</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>8444929782</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>ERIC LEE SINCLAIR III</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>38808</noOfUnitsSold>
            <aggregateMarketValue>1538737.20</aggregateMarketValue>
            <noOfUnitsOutstanding>173018999</noOfUnitsOutstanding>
            <approxSaleDate>05/21/2025</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>05/21/2025</acquiredDate>
            <natureOfAcquisitionTransaction>Exercise of Stock Options</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>38808</amountOfSecuritiesAcquired>
            <paymentDate>05/21/2025</paymentDate>
            <natureOfPayment>Cash</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <remarks>The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale.
</remarks>
        <noticeSignature>
            <noticeDate>05/21/2025</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>02/19/2025</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/ ERIC LEE SINCLAIR III</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
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144
0001998250
XXXXXXXX
LIVE
0001990354
WAYSTAR HOLDING CORP
001-42125
1550 Digital Drive, #300
Lehi
UT
84043
8444929782
ERIC LEE SINCLAIR III
Officer
Common
Morgan Stanley Smith Barney LLC Executive Financial Services
1 New York Plaza
8th Floor
New York
NY
10004
38808
1538737.20
173018999
05/21/2025
NASDAQ
Common
05/21/2025
Exercise of Stock Options
Issuer
N
38808
05/21/2025
Cash
Y
The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale.
05/21/2025
02/19/2025
/s/ ERIC LEE SINCLAIR III