The compliance with treatment of acute otitis media in 300 pediatric outpatients was evaluated. Complete compliance in taking prescribed antibiotics was noted in 7.3% of the patients. Pharmacists dispensed less than prescribed amounts of antibiotics to 15% of patients. Bottles were incorrectly labeled 3% of the time. Volumes of 130 "teaspoons" examined varied from 2 to 9 ml. Parental understanding of the illness and of the effects of medication was inadequate and erroneous in many instances. Parents gave fewer than the prescribed number of doses in 36% of cases, and therapy was discontinued early in 37%. Recommendations for improving the quality of therapy for ambulatory pediatric patients are outlined.