Timothy R. Wassenaar, MD
Hematology & Oncology Physician · Waukesha, WI
Timothy R. Wassenaar, MD is a hematology & oncology physician with a practice address in Waukesha, Wisconsin, and NPI 1518928993, issued on Mar 28, 2006. Check the license (Wisconsin 46327, as entered in NPPES) on the Wisconsin Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Timothy R. Wassenaar
- Credential
- MD
- Primary taxonomy
- Hematology & Oncology Physician 207RH0003X
- License number
- 46327 WI
Self-reported in NPPES; status is on the state search - Practice location
- N16W24131 Riverwood Dr, Waukesha, WI 53188
- Phone
- (262) 696-5690
- Enumerated
- Mar 28, 2006
- Record last updated
- Jan 10, 2024
- Medicaid ID
- 34691700 WI
- Medicare enrollment
- Enrolled (PECOS I20051020000367); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest hematology & oncology physician records → All 295 in Wisconsin → Look up another NPI →
Also registered at N16W24131 Riverwood Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Abigail Boesl, AUDAudiologist1558256115
- Christopher Burnett, MDMOHS-Micrographic Surgery Physician1780863779
- Kathleen Bussen, PTPhysical Medicine & Rehabilitation Physician1285133504
- Ryan Condon, MS, LCGCGenetic Counselor (M.S.)1003601295
- Katie DammenAdult Health Nurse Practitioner1083449441
- Laura GildersleevePhysician Assistant1356074850
Verify Timothy R. Wassenaar in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWisconsin Medical Examining Board
Search for license 46327Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
64% more Medicare Part D claims than the average hematology & oncology physician in 2024
1,434 Medicare Part D claims for 164 beneficiaries, against an average of 877 among the 10,784 providers of this specialty who prescribed in Part D. Brand-name drugs were 33% of claims. 41 claims were for opioids.
Most prescribed
- Acyclovir198 claims
- Eliquis139 claims
- Hydroxyurea126 claims
- Dexamethasone63 claims
- Revlimid58 claims
- Warfarin Sodium53 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.
Bills Medicare through one group practice
- Prohealth Medical Group IncOconomowoc, WI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Timothy R. Wassenaar among 295 hematology & oncology physician records in Wisconsin
Timothy R. Wassenaar, MD is one of 295 hematology & oncology physician records with a practice address in Wisconsin. 82% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 8% of them.
- NPI issued2006 · 8% of these records are older, 59% newer
- In a Medicare fileYes · 82% of these records are
- In the CMS Doctors and Clinicians fileYes · 74% of these records are
- Graduated2002 · median 2004 among the 217 with a school on file
- Record last updated2024 · 51% 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 Wisconsin 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 Wisconsin
There are 295 hematology & oncology physician records in Wisconsin.
All 295 in Wisconsin → Every provider in Waukesha → Hematology & Oncology Physician nationwide →
The 8 hematology & oncology physician records with the nearest ZIP codes
- Christopher Hake, MDWaukesha, WI 531881871544619
- Kathleen Hemauer, M.D.Waukesha, WI 531881326467234
- Peter Johnson, M.D.Waukesha, WI 531881407948763
- Jonathan Kapke, DOWaukesha, WI 531881093058372
- Laura Raftery, M.D.Waukesha, WI 531881992862551
- Mohammad Raza, M.D.Waukesha, WI 531881952585788
- Federico Sanchez, M.D.Waukesha, WI 531881396710836
- Derek Serna, M.D.Waukesha, WI 531881205044773
Common questions
What is Timothy R. Wassenaar, MD's NPI number?
Timothy R. Wassenaar, MD's National Provider Identifier (NPI) is 1518928993, issued on Mar 28, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Timothy R. Wassenaar, MD located?
The NPPES record lists a practice address at N16W24131 Riverwood Dr, Waukesha, WI, 53188. Phone: (262) 696-5690. Providers update this record themselves, so call before visiting.
How can I verify Timothy R. Wassenaar, MD's license?
NPPES lists Wisconsin license number 46327, as entered by the provider. Search the Wisconsin Medical Examining Board at https://dsps.wi.gov/Pages/BoardsCouncils/MEB/Default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Timothy R. Wassenaar, MD prescribe under Medicare Part D?
In 2024, Timothy R. Wassenaar, MD had 1,434 Medicare Part D claims for 164 beneficiaries; the average among hematology & oncology physician prescribers was 877. Part D covers Medicare prescriptions only.
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.