Little is known about the attrition of physicians trained in internal medicine (IM). The authors sought to examine career paths, disciplinary actions, and American Board of Medical Specialties (ABMS) certification status of IM residents.Three datasets were combined to study 66,881 residents in Accreditation Council for Graduate Medical Education-accredited IM residency programs nationwide from 1995 to 2004. Group differences (among an American Board of Internal Medicine [ABIM]-certified cohort; an ABMS-certified cohort (but not ABIM-certified); and a noncertified cohort) in IM residency performance ratings, specialty certification status, year of initial IM training, and medical board disciplinary actions were examined. Analyses included chi-square tests, analysis of variance, pairwise comparisons, and logistic regressions.Ninety-five percent of IM residents obtained ABIM certification; 1.6% received ABMS certification in another specialty; 3.4% received no ABMS specialty certification, of which 74.3% have a current medical license; and 66.6% self-reported IM as their primary specialty. During residency, the ABIM cohort performed better than those who never obtained ABIM certification. Disciplinary actions were lowest for the ABIM cohort (1.2%), 2.4% for the ABMS cohort, and highest and more severe for the noncertified cohort (6.0%).Only 5% of IM residents do not achieve IM certification. IM resident attrition minimally impacts physician supply, though those without certification appear to contribute disproportionately to poor physician performance indicators. Improved tracking of the U.S. physician workforce could aid policy makers in predicting manpower shifts in certain specialty areas, both during and after residency training.