OBJECTIVE: To assess three prescribing strategies for sore throat. DESIGN: Randomised follow up study. SETTING: 11 general practices in the South and West region. SUBJECTS: 716 patients aged 4 years and over with sore throat and an abnormal physical sign in the throat; 84% had tonsillitis or pharyngitis. Patients were randomised to three groups: prescription for antibiotics for 10 days (group 1,246 patients); no prescription (group 2,230 patients); or prescription for antibiotics if symptoms were not starting to settle after three days (group 3; 238 patients). MAIN OUTCOME MEASURES: Duration of symptoms; satisfaction and compliance with and perceived efficacy of antibiotics; time off school or work. Outcomes were documented in 582 subjects (81%). RESULTS: Median duration of antibiotic use differed significantly in the three groups (10 v 0 v 0 days, P < 0.001); 69% of patients in group 3 did not use their prescription. The proportion of patients better by day 3 did not differ significantly (37% v 35% v 30%, P = 0.28), nor did the duration of illness (median 4 v 5 v 5 days, P = 0.39), days off work or school (median 2 v 2 v 1, P = 0.13), or proportion of patients satisfied (96% v 90% v 93%, P = 0.09), although group 1 had fewer days of fever (median 1 v 2 v 2 days, P = 0.04). More patients in group 1 thought the antibiotics were effective (87% v 55% v 60%, P < 0.001) and intended coming to the doctor in future attacks (79% v 54% v 57%, P < 0.001). "Legitimation" of illness-to explain to work or school (60%) or family or friends (37%)-was an important reason for consultation. Patients who were more satisfied got better more quickly, and satisfaction related strongly to how well the doctor dealt with patient's concerns. CONCLUSION: Prescribing antibiotics for sore throat only marginally affects the resolution of symptoms but enhances belief in antibiotics and intention to consult in future when compared with the acceptable strategies of no prescription or delayed prescription. Psychosocial factors are important in the decision to see a general practitioner and in predicting the duration of illness.