Because widely held stereotypes characterize obese people as less intelligent, unhappy, lacking in self control and more prone to psychological problems, we tested whether obese appearance alone would affect medical students’ decisions about the diagnosis and management of simulated patients. We videotaped 4 patient simulators presenting each of 4 cases in 2 states: normal and obese (by using padding and bulky clothing). Seventy-two clinical students at 2 medical schools viewed the cases and answered questions about diagnostic tests and management. We found the expected biases toward patients when in their obese form as well as pessimism about patient compliance and success of therapy, but there were no significant differences in tests or treatments ordered except where appropriate for an obese patient (e.g., weight reduction diet). Thus, the appearance of obesity alone biased the students’ impressions of the patients, but did not affect diagnostic test ordering.