Four hundred children with streptococcal pharyngitis were treated randomly with single injections in groups of 100 each (1) with 600,000 units of penicillin G benzathine, (2) 1.2 million units of penicillin G benzathine, (3) 600,000 units of penicillin G benzathine and 600,000 units of penicillin G procaine, or (4) 900,000 units of penicillin G benzathine and 300,000 units of penicillin G procaine. Clinical response and severity of local reaction were judged in a double-blind manner at 24, 48, and 72 hours; throat cultures were taken then, and at 10, 21, and 42 days. Although the clinical response to 900,000 units of penicillin G benzathine and 300,000 units of penicillin G procaine was equal to 1.2 million units of penicillin G benzathine, the former cleared the streptococci more quickly, greatly reduced the incidence and severity of local reactions, and offered optimal therapy for streptococcal pharyngitis in the pediatric age group.