An exodus of male physicians from primary care is driving a marked shift in the U.S. physician workforce toward medical-specialty practice, according to a national study by the Center for Studying Health System Change (HSC). Two factors have helped mask the severity of the shift—a growing proportion of female physicians, who disproportionately choose primary care, and continued reliance on international medical graduates (IMGs), who now account for nearly a quarter of all U.S. primary care physicians. Since 1996-97, a 40 percent increase in the female primary care physician supply has helped to offset a 16 percent decline in the male primary care physician supply relative to the U.S. population. At the same time, primary care physicians’ incomes have lost ground to both inflation and medical and surgical specialists’ incomes. And women in primary care face a 22 percent income gap relative to men, even after accounting for differing characteristics. If real incomes for primary care physicians continue to decline, there is a risk that the migration of male physicians will intensify and that female physicians may begin avoiding primary care—trends that could aggravate a predicted shortage of primary care physicians.Thanks to CMS, we can count on further shortages.