OBJECTIVE: To assess the information pharmaceutical sales representatives provide to physicians. DATA SOURCES: A MEDLINE search from January 1966 to May 1996 was done using combinations of the terms pharmaceutical industry, drug information services, drug utilization, physician's practice patterns and prescriptions, and drugs. Studies identified from this search were supplemented by material from my personal library. STUDY SELECTION: Studies had to be conducted in industrialized countries, based on direct observations of actual physician and sales representative contacts, and reporting quantitative results on the quality of information transmitted. SYNTHESIS: Four studies were included. Representatives usually mentioned the indications for their drugs, but omitted safety information. Representatives' information frequently contained inaccuracies. CONCLUSION: Sales representatives present only selected, usually positive, information about their products. Canadian doctors should not be passive recipients of information provided by sales representatives. Physicians who choose to continue to see representatives must critically compare the information they get from them with that contained in scientific publications.