Generally, all Foreign Medical Graduates will have to complete 3 years of Post Graduate Residency in the U.S. prior to obtaining a full-fledged license to practice medicine. The minimum requirement for admission into a residency program is passing of the ECFMG certification and USMLE exams steps 1 and 2. The ECFMG website has useful information about the process.
The Service may also require that a candidate complete USMLE step 3 and obtain a limited license to practice medicine before issuing an H-1B Non-immigrant Visa to enter and participate in the Residency program.