Doctors in different countries completed a questionnaire relating to the importance they attributed to eight possible sources of information about a new drug, their estimation of patients' expectations of the doctor prescribing drugs under specific circumstances and their therapeutic response to common clinical general practice situations. There were major differences between the stated behaviour of doctors in different countries with regard to the importance they attached to the eight sources of information on drugs. While doctors agreed on the importance of books and journals and on the unimportance of patients, nurses and other paramedicals, there was a major disagreement about the importance of drug company representatives: this source of information about new drugs was rated high in Sweden and Yugoslavia and low in Britain and Belgium. Doctors also differed in their estimation of patients' expectations of how they would prescribe and how they responded to the clinical problems. The differences, which might be due to differences in education about therapeutics or to cultural differences between countries, are important because of the high cost of drugs bills in all countries.