The influence of an educational program on the diagnosis and treatment of pharyngotonsillitis was evaluated in three outpatient clinics in northern Israel during two periods. During both periods--1 January to 31 March 1988 (baseline phase) and 1 January to 31 March 1989 (study phase)--clinical data of all patients for whom antibiotics were prescribed were recorded on special forms, which included the patient's diagnosis and the antibiotic prescribed. In November 1988, 2 months before the study phase, two 1 h sessions on pharyngitis were given by the study physicians to the entire medical staff of two clinics (Clinics B and C), and written material was distributed. A third clinic (Clinic A) served as the control. A comparison of the prescribing habits during the two phases showed that during the study phase the total number of antibiotics prescriptions for pharyngitis declined significantly in Clinics B and C, while the percentage of prescriptions for penicillin V rose with the concomitant decline of amoxycillin. There were no significant changes in prescribing habits in the control clinic. These results show that a modest 2 h educational program involving direct contact with the entire medical staff of the community outpatient clinics can improve the diagnosis of pharyngotonsillitis and reduce both the inappropriate use of antibiotics in general, and the substitution of more expensive antibiotics for cheaper, equally effective ones.