Streptococcal impetigo associated with atopic dermatitis has dramatically increased from 1989 to 1994 in outpatients visiting our hospital, totalling 174 cases. The most frequent causative agents were group A streptococci (Streptococcus pyogenes, 70.7%) followed by group G (19.5%) and group B (9.8%). Streptococcus was isolated singly in 28.2% of cases and in concomitant with Staphylococcus aureus (S. aureus) in 71.8%. Major clinical features of streptococcal impetigo, especially caused by group A streptococci, were non-bullous pustules with thick crusted ceiling. Impetigo caused by group G or B streptococci generally formed smaller sized pustules of fewer numbers. Impetigo was usually present, associated with severe eczematous lesions. Various degrees of fever were noticed in 32.8% (group A, 39.8%; group G, 17.6%; group B, 11.8%) during active stages. The lesions on the face often resembled Kaposi's varicelliform eruption in any group. Systemic antimicrobial agents were administered in 71.3% of cases and the remainder were treated with topical antibiotics (oxytetracycline hydrochloride) or disinfectants (povidone-iodine). Recurrence occurred within a month in 38.0% of cases treated with topical agents only and in 17.7% treated with systemic antimicrobial agents. Antimicrobial susceptibility tests and the results of treatment seem to indicate that cephems, as well as penicillins, are the first choice of treatment for streptococcal impetigo.