A 1-month elective course in clinical pharmacology in primary care has been developed and is offered six times a year for fourth-year medical students. The major course objective is to teach the student to apply the principles of rational therapeutics in the routine practice of primary care. The faculty includes clinical pharmacists and primary care physicians from the Department of Family Medicine. Two students each month rotate through a combined didactic and experiential curriculum oriented toward the rational selection and monitoring of drugs in inpatient and outpatient settings. Students interact daily with faculty members and have ample opportunity to evaluate drug therapy regimens and assist in designing new therapeutic strategies. Students are evaluated on their performance in conferences, written consultations, and oral case challenges. Evaluations by students indicate that this elective is a valuable educational experience.