The efficacy of cefadroxil, an orally administered broad spectrum cephalosporin, was compared with that of penicillin V in several studies comprising more than 550 children with group A beta-haemolytic streptococcal (GABHS) pharyngitis. Both drugs alleviated clinical signs and symptoms and eradicated GABHS from the upper respiratory tract within 18 to 24 hours of the initiation of therapy. Approximately 8% of the patients treated with either cefadroxil or penicillin V had strains of GABHS isolated from 1 of their follow-up throat cultures which were identical to the strains isolated from their initial throat cultures, and were considered bacteriological treatment failures. Compliance was greater than 90% with all of the regimens used, but was significantly better with cefadroxil given as a 30 mg/kg dose once daily than with penicillin V given 3 times daily. There were no serious adverse reactions with either drug. Thus, cefadroxil was shown to be well tolerated and as effective as the standard agent, oral penicillin V, in the treatment of GABHS pharyngitis in children.