Seng M. Leong, MD
Internal Medicine Physician · Barrington, IL
Seng M. Leong, MD is an internal medicine physician with a practice address in Barrington, Illinois, and NPI 1487750790, issued on Sep 15, 2006. Check the license (Illinois 036-055809, as entered in NPPES) on the Illinois Department of Financial and Professional Regulation; the Medicare figures below come from public CMS files.
- Name
- Seng M. Leong
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 036-055809 IL
Self-reported in NPPES; status is on the state search - Practice location
- 27750 W Highway 22, Barrington, IL 60010
- Phone
- (847) 381-5800
- Enumerated
- Sep 15, 2006
- Record last updated
- Mar 31, 2025
- Fax
- (847) 381-5873
- Medicaid ID
- 03655809 IL
- Medicare enrollment
- Enrolled (PECOS I20100130000127); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 7,238 in Illinois → Look up another NPI →
Also registered at 27750 W Highway 22
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Seng M. Leong 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 036-055809Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
4.9 times the Medicare Part D claims of the average internal medicine physician in 2024
15,554 Medicare Part D claims for 978 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 10% of claims. 351 claims were for opioids.
Most prescribed
- Atorvastatin Calcium1,050 claims
- Amlodipine Besylate876 claims
- Losartan Potassium537 claims
- Levothyroxine Sodium535 claims
- Metoprolol Succinate515 claims
- Lisinopril424 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
- Advocate Health And Hospitals CorporationBuffalo Grove, IL
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Seng M. Leong among 7,238 internal medicine physician records in Illinois
Seng M. Leong, MD is one of 7,238 internal medicine physician records with a practice address in Illinois. 73% 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 7% of them.
- NPI issued2006 · 7% of these records are older, 61% newer
- In a Medicare fileYes · 73% of these records are
- In the CMS Doctors and Clinicians fileYes · 50% of these records are
- Graduated1969 · median 2003 among the 3,580 with a school on file
- Record last updated2025 · 47% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a Illinois practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
17 internal medicine physician records list a practice address in Barrington
They are 17 of the 756 NPPES records with a practice address in Barrington, and 7,238 internal medicine physician records in Illinois.
All 7,238 in Illinois → Every provider in Barrington → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Roseann Brady, D.O.North Barrington, IL 600101477604106
- Melinda Einfalt, MDBarrington, IL 600101821084393
- Behzad Farah, MDBarrington, IL 600101689630915
- Rachel George, MD, MBASouth Barrington, IL 600101639109002
- John Gong, MDBarrington, IL 600101962414623
- Galina Goode, M.D.Barrington, IL 600101336209618
- Shahid Ilahi, M.D.Lake Barrington, IL 600101508867078
- Leo Kelly, M.D.Barrington, IL 600101386704666
Common questions
What is Seng M. Leong, MD's NPI number?
Seng M. Leong, MD's National Provider Identifier (NPI) is 1487750790, issued on Sep 15, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Seng M. Leong, MD located?
The NPPES record lists a practice address at 27750 W Highway 22, Barrington, IL, 60010. Phone: (847) 381-5800. Providers update this record themselves, so call before visiting.
How can I verify Seng M. Leong, MD's license?
NPPES lists Illinois license number 036-055809, 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 Seng M. Leong, MD prescribe under Medicare Part D?
In 2024, Seng M. Leong, MD had 15,554 Medicare Part D claims for 978 beneficiaries; the average among internal medicine physician prescribers was 3,176. 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.