Importance: Historically, the US physician workforce has included a large number of international medical graduates (IMGs). Recent US immigration policies may affect the inflow of IMGs, particularly those who are citizens of Muslim-majority nations. Objectives: To provide an overview of the characteristics of IMGs from Muslim-majority nations, including their contributions to the US physician workforce, and to describe trends in the number of applications for certification to the Educational Commission for Foreign Medical Graduates between 2019 and 2018, both overall and for citizens of Muslim-majority nations. Design, Setting, and Participants: This cross-sectional study, which included 1 065 606 US physicians listed in the 2019 American Medical Association Physician Masterfile and 156 017 applicants to the Educational Commission for Foreign Medical Graduates certification process between 2009 and 2018, used a repeated cross-sectional study design to review the available data, including country of medical school attended, citizenship when entering medical school, and career information, such as present employment, specialty, and type of practice. Exposures: Country of citizenship when entering medical school. Main Outcomes and Measures: Physician counts and demographic information from the 2019 American Medical Association Physician Masterfile and applicant data from the Educational Commission for Foreign Medical Graduates from 2009 to 2018. Results: Of 1 065 606 physicians in the American Medical Association Physician Masterfile, 263 029 (24.7%) were IMGs, of whom 48 354 were citizens of Muslim-majority countries at time of entry to medical school, representing 18.4% of all IMGs. Overall, 1 in 22 physicians in the US was an IMG from a Muslim-majority nation, representing 4.5% of the total US physician workforce. More than half of IMGs from Muslim-majority nations (24 491 [50.6%]) come from 3 countries: Pakistan (14 352 [29.7%]), Iran (5288 [10.9%]), and Egypt (4851 [10.0%]). The most prevalent specialties include internal medicine (10 934 [23.6%]), family medicine (3430 [7.5%]), pediatrics (2767 [5.9%]), and psychiatry (2251 [4.8%]), with 18 229 (38.1%) practicing in primary care specialties. The number of applicants for Educational Commission for Foreign Medical Graduates certification from Muslim-majority countries increased from 2009 (3227 applicants) to 2015 (4244 applicants), then decreased by 2.1% in 2016 to 4254 applicants, 4.3% in 2017 to 4073 applicants, and 11.5% in 2018 to 3604 applicants. Much of this decrease could be attributed to fewer citizens from Pakistan (1042 applicants in 2015 to 919 applicants in 2018), Egypt (493 applicants in 2015 to 309 applicants in 2018), Iran (281 applicants in 2015 to 182 applicants in 2018), and Saudi Arabia (337 applicants in 2015 to 163 applicants in 2018) applying for certification. Conclusions and Relevance: Based on the findings of this study, the number of ECFMG applicants from Muslim-majority countries decreased from 2015 to 2018. The US physician workforce will continue to rely on IMGs for some time to come. To the extent that citizens from some countries no longer seek residency positions in the US, gaps in the physician workforce could widen.