Mark Walshauser, M.D.
NPI 1306020664 · Hematology & Oncology Physician · O Fallon, IL
Enrolled with Medicare as Practitioner - Hematology/Oncology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Mark Walshauser, M.D. is a Hematology & Oncology Physician provider in O Fallon, IL (NPI 1306020664).
Provider details
- NPI number
- 1306020664
- Entity type
- Individual
- Primary specialty
- Hematology & Oncology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- 2010024540 (MO)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
18 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
3 documented practice locations
- Medicare service volume (vs. specialty peers)25% of score
12,948 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Injection of Additional New Drug Or Substance Into Vein96375 | 1,222 | $14 |
| Blood Test, Comprehensive Group of Blood Chemicals80053 | 1,022 | $10 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 988 | $123 |
| Insertion of Needle Into Vein for Collection of Blood Sample36415 | 907 | $9 |
| Lactate Dehydrogenase (enzyme) Level83615 | 720 | $6 |
| Visit Complexity Inherent to Evaluation and Management Associated With Medical Care Services That Serve As the Continuing Focal Point for All Needed Health Care Services And/Or With Medical Care Services That Are Part of Ongoing Care Related to a Patient'SG2211 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 38 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Anastrozole | 129 | 47 |
| Ondansetron Hcl | 108 | 80 |
| Prochlorperazine Maleate | 94 | 78 |
| Prednisone | 89 | 29 |
| Hydrocodone/Acetaminophenbrand: Hydrocodone-Acetaminophen | 67 | 21 |
| Palbociclibbrand: Ibrance | 50 | — |
| Tramadol Hcl | 46 |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$9,265 across 93 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Additional practice locations (2)
- 12860 Troxler Ave Ste 135Highland, IL 62249-2898Phone: (618) 416-7970Fax: (618) 416-7971
- Broadway Plaza Suite 1Sparta, IL 62286-1800Phone: (618) 416-7970Fax: (618) 416-7971
Registry dates
- Enumerated
- 2007-12-21
- Last updated
- 2023-12-12
- Certified
- 2023-12-08
Frequently asked questions
- What is Mark Walshauser's NPI number?
- Mark Walshauser's National Provider Identifier (NPI) is 1306020664, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Mark Walshauser's specialty?
- Mark Walshauser is listed in the NPPES registry with a primary specialty of Hematology & Oncology Physician (Allopathic & Osteopathic Physicians).
- Where is Mark Walshauser located?
- Mark Walshauser's practice location on file with NPPES is 321 Regency Park Ste 100, O Fallon, IL 62269-1887.
- What is Mark Walshauser's phone number?
- The practice phone number listed in the NPPES registry for Mark Walshauser is (618) 416-7970.
- Does Mark Walshauser accept Medicare?
- Mark Walshauser is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Mark Walshauser's NPI active?
- Yes — Mark Walshauser's NPI (1306020664) is active in the NPPES registry as of the last update on 2023-12-12.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.