Purpose: To assess medical students' and housestaff's knowledge, attitudes, and behaviors regarding safe prescribing. Method: In 2003, 214 housestaff (interns and residents) and 77 medical students in medicine and surgery at Barnes-Jewish Hospital, St. Louis, Missouri, were asked to complete an anonymous, self-administered questionnaire about safe prescribing. Questions asked about training in and attitudes about safe-prescribing and current prescribing behaviors. Fisher exact test was used to compare attitudes and behaviors among subgroups. Results: Of the 175 (60%) respondents, 73 (59%) of 123 housestaff and eight (15%) of 52 students agreed that their safe-prescribing training was adequate (p < .001), and 145 (83%) total respondents agreed that prescribing errors were unacceptable. Respondents reported always doing the following: 156 (89%) checked prescribing information before prescribing new drugs, 131 (75%) checked for drug allergies, 103 (59%) double-checked dosage calculations, 98 (56%) checked for renal impairment, and 53 (30%) checked for potential drug-drug interactions. Conclusion: Routine use of safe medication prescribing behaviors among housestaff and medical students was poor. Contributing factors may have included inadequate training and a culture that does not support safe prescribing. Effective strategies to increase safe medication prescribing need to be identified and implemented.