Prescription of antibiotics in Sweden varies between countries within a range of 13-20 DDD/1000 inhabitants/day. In Malmöhus county, which accounts for the highest prescription rate, the amounts and proportions of erythromycin and tetracyclin prescribed are particularly large. All prescriptions for antibiotics dispensed in half of the pharmacies in the county during a one-week period were examined with respect to type of antibiotic and category of physician responsible for the prescription. Among 5,165 antibiotic prescriptions examined, broad spectrum antibiotics were more frequent in urban than in rural areas, and were more often prescribed by hospital physicians and private practitioners than by district physicians. Erythromycin was particularly often prescribed by paediatricians, the frequency being comparable to that of phenoxymethylpenicillin. Retrospective analysis of consultations at the ENT and paediatric clinics for respiratory tract infections showed that phenoxymethylpenicillin was not always the drug of choice by hospital physicians, despite a recommendation to that effect by the Board of Health and Welfare. The findings suggest that the choice of antibiotics is determined not only by medically relevant factors and Board recommendations but also by the habits of the consulting physicians.