The efficacy of 3-day treatment with a combined clavulanate/amoxicillin preparation (Clavamox combination dry syrup for pediatric cases) and 10-day treatment with amoxicillin against pediatric pharyngolaryngitis and tonsillitis caused by Group A β-hemolytic Streptococcus was compared. Among the patients included in the efficacy evaluation (54 from the clavulanate/amoxicillin group and 43 from the amoxicillin group), the clinical response rate on completion of treatment was 98.1 % in the clavulanate/amoxicillin group and 92.9 % in the amoxicillin group, thus supporting the equivalent efficacy of these two therapies. The Group A β-hemolytic Streptococcus eradication rate at approximately 1-2 weeks after completion/discontinuation of treatment was 65.4 % in the clavulanate/amoxicillin group and 85.4 % in the amoxicillin group. Even in cases from which the pathogen continued to be isolated, relapse/recurrence of clinical symptoms was seldom seen. Urinalysis, conducted to assess the presence or absence of acute glomerulonephritis, revealed no abnormality in any patient. These results suggest that 3-day treatment with this clavulanate/amoxicillin preparation is expected to provide a valid means of treating pediatric pharyngolaryngitis and tonsillitis caused by Group A β-hemolytic Streptococcus.