Mark Andrew Walshauser, M.D.
Hematology & Oncology Physician · O Fallon, IL
Mark Andrew Walshauser, M.D. is a hematology & oncology physician with a practice address in O Fallon, Illinois, and NPI 1306020664, issued on Dec 21, 2007. Check the license (Illinois 036128331, as entered in NPPES) on the Illinois Department of Financial and Professional Regulation; the Medicare figures below come from public CMS files.
- Name
- Mark Andrew Walshauser
- Credential
- M.D.
- Primary taxonomy
- Hematology & Oncology Physician 207RH0003X
- License numbers
- 036128331 IL
2010024540 MO
Self-reported in NPPES; status is on the state search - Practice location
- 321 Regency Park Ste 100, O Fallon, IL 62269
- Phone
- (618) 416-7970
- Enumerated
- Dec 21, 2007
- Record last updated
- Dec 12, 2023
- Fax
- (618) 416-7971
- Medicaid ID
- 036128331 IL
- Medicare enrollment
- Enrolled (PECOS I20140711000552); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest hematology & oncology physician records → All 666 in Illinois → Look up another NPI →
Also registered at 321 Regency Park Ste 100
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Rachael Demattei, APRNNurse Practitioner1891443289
- Bachir Farah, M.D.Hematology & Oncology Physician1336370915
- Justin Floyd, DOMedical Oncology Physician1629164678
- Bassam Maalouf, M.D.Hematology & Oncology Physician1720173438
- Ryan Mueller, MDRadiation Oncology Physician1912571654
- Julianne Tomac, DNP, FNP-CFamily Nurse Practitioner1245018944
Verify Mark Andrew Walshauser in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIllinois Department of Financial and Professional Regulation
Search for license 036128331Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
75% more Medicare Part D claims than the average hematology & oncology physician in 2024
1,534 Medicare Part D claims for 283 beneficiaries, against an average of 877 among the 10,784 providers of this specialty who prescribed in Part D. Brand-name drugs were 20% of claims. 181 claims were for opioids.
Most prescribed
- Anastrozole129 claims
- Ondansetron Hcl108 claims
- Prochlorperazine Maleate94 claims
- Prednisone89 claims
- Hydrocodone-Acetaminophen67 claims
- Ibrance50 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The practice group's MIPS final score for 2023 (Medicare payment program): 77.7 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023, group reporting; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $9,264.75
93 payments; by number, the most common kind was food and beverage; the largest payer was Regeneron Pharmaceuticals, Inc. The 8,560 providers of this specialty with any payment received $7,481.41 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- Cancer Care Specialists OF Central Illinois SCO Fallon, IL
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mark Andrew Walshauser among 666 hematology & oncology physician records in Illinois
Mark Andrew Walshauser, M.D. is one of 666 hematology & oncology physician records with a practice address in Illinois. 84% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2007, is newer than 43% of them.
- NPI issued2007 · 43% of these records are older, 48% newer
- In a Medicare fileYes · 84% of these records are
- In the CMS Doctors and Clinicians fileYes · 69% of these records are
- Graduated2006 · median 2003 among the 461 with a school on file
- Record last updated2023 · 49% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RH0003X and a Illinois practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Hematology & Oncology Physician providers in Illinois
There are 666 hematology & oncology physician records in Illinois.
All 666 in Illinois → Every provider in O Fallon → Hematology & Oncology Physician nationwide →
The 8 hematology & oncology physician records with the nearest ZIP codes
- Bachir Farah, M.D.O Fallon, IL 622691336370915
- Bassam Maalouf, M.D.O Fallon, IL 622691720173438
- Muhammad Ali, M.DQuincy, IL 623011306826250
- Kellie Flippin, MDQuincy, IL 623011013193705
- Christian Khoury, MDQuincy, IL 623011477694867
- Daniel Koh, MDQuincy, IL 623011306946033
- Mohammed Memon, M.D.Quincy, IL 623011164577102
- Raymond Smith, MDQuincy, IL 623011477526259
Common questions
What is Mark Andrew Walshauser, M.D.'s NPI number?
Mark Andrew Walshauser, M.D.'s National Provider Identifier (NPI) is 1306020664, issued on Dec 21, 2007. An NPI identifies a provider in billing; it is not a license.
Where is Mark Andrew Walshauser, M.D. located?
The NPPES record lists a practice address at 321 Regency Park Ste 100, O Fallon, IL, 62269. Phone: (618) 416-7970. Providers update this record themselves, so call before visiting.
How can I verify Mark Andrew Walshauser, M.D.'s license?
NPPES lists Illinois license number 036128331, as entered by the provider. Search the Illinois Department of Financial and Professional Regulation at https://idfpr.illinois.gov/checklicense.html. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mark Andrew Walshauser, M.D. prescribe under Medicare Part D?
In 2024, Mark Andrew Walshauser, M.D. had 1,534 Medicare Part D claims for 283 beneficiaries; the average among hematology & oncology physician prescribers was 877. Part D covers Medicare prescriptions only.
What is Mark Andrew Walshauser, M.D.'s MIPS final score?
The 2023 MIPS final score is 77.7 of 100, reported for the practice group. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.