MIC of cefadroxil (CDX) against A group beta-Streptococcus was distributed between 0.05-0.2 microgram/ml, that is, more susceptible than cephalexin (CEX) an cefaclor (CCL), and susceptible to tetracycline (TC), erythromycin (EM), lincomycin (LCM) resistant strains. Serum level was higher than CCL administered orally at the same dose, and urinary excretion ratio after oral administration was good similarly to CEX and CCL. Patients treated were mostly scarlet fever and upper respiratory tract infections as acute tonsillitis and lacunar tonsillitis. They responded well to CDX at a daily dose of 30 mg/kg divided into 3-4 times. All cases of scarlet fever became normal temperature within 2 days. Among 14 cases in which A group beta-hemolytic Streptococcus was detected by pharyngeal sputum culture at admission, 11 cases became negative on the 1st day. This result was superior to CEX, when this drug was administered orally at a daily dose of 40-60 mg/kg, bacteria became negative at the ratio of 73.3% on the 2nd day. CDX was effective for acute tonsillitis, lacunar tonsillitis, acute bronchitis, impetigo and maxillary lymphadenitis in which numerous A group beta-Streptococcus, Staphylococcus aureus and Haemophilus influenzae were proven, as well as for acute urinary tract infection due to Escherichia coli. Clinical results of CDX in totalling 69 cases were excellent in 63 cases, good in 6 cases, efficacy ratio being 100%. No local nor systemic side effects were observed in 69 cases including maximum 11 days' treatment, as well as no effect was noticed on hepatic and renal functions. From the above results, it was concluded that satisfactory treatment results may be obtained with CDX dry syrup for children at a daily dose of 20-50 mg/kg divided into 3-4 times in acute infections due to CDX susceptible pathogens.