Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Mark William Onaitis, MD

Individual provider Thoracic Surgery (Cardiothoracic Vascular Surgery) Physician · NPI 1841310638

Mark William Onaitis, MD practises Thoracic Surgery in San Diego, California. Graduated from Duke University School of Medicine in 1997, 29 years ago. Practices with Regents of the University of California, a 2,061-clinician group, accepts Medicare assignment and offers telehealth. Licensed in California.

Years since qualifying
29
Trained at
Duke University School of Medicine
Licensed in
CA
In the registry since
2007
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

200 W Arbor Dr
San Diego, CA 92103-9000
Phone: (858) 657-7777
Fax: (858) 657-5058
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Thoracic Surgery (Cardiothoracic Vascular Surgery) Physician (primary) Taxonomy 208G00000X · Licence A144886 (CA)

Record details

NPI number1841310638
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedMarch 29, 2007
Last updated in NPPESFebruary 21, 2019

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyTHORACIC SURGERY
Medical schoolDUKE UNIVERSITY SCHOOL OF MEDICINE
Graduated 1997 (29 years in practice)
Group practice Regents Of The University Of California — 2061 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations2 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Upper gastrointestinal (GI) endoscopy for acid reflux 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients116
Services billed 234 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Compensation for services other than consulting , including serving as faculty or as a speaker at a venue other than a continuing education program $5,000 1 payment
Consulting Fee $3,163 2 payments
Food and Beverage $1,009 14 payments · a meal or drink at a meeting or visit, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Regents of the University of California

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 2061 clinicians in the practice; 12 are shown here.

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