Professional ethics require physicians to put their patients’ interests ahead of their own and allocate limited medical resources efficiently. Insight into physicians’ adherence to these principles requires an understanding of the trade-offs between self and other (altruism) and between reducing differences in payoffs (equality) and increasing total payoffs (efficiency). In a new PNAS study, Drs. Jing Li and Lawrence P. Casalino and colleagues measure social preferences among U.S. physicians to distinguish empirically between altruism and equality-efficiency orientation and measure both trade-offs at the level of the individual subject. They also compare the measured social preferences of physicians with those of a representative sample of Americans, an “elite” subsample of Americans, and a nationwide sample of medical students. Findings show that physicians are twice as likely to be altruistic as all other samples, 32% compared to 15 to 17%, but indistinguishable from the general population in equality-efficiency orientation. This suggests that policymakers may not rely on physician professionalism alone to ensure high-quality care or efficient use of medical resources.