The aim of this prospective study was to compare the clinical picture of contagious impetigo (C.I.) with the causative organism and to generate data of the susceptibility of bacteria as the basis for adequate therapy.In 126 patients with C.I. (86 children, 66 of them younger than 10 years) bacterial swabs were taken and antibiotic sensitivity testing for isolated organisms was tested.In all cases in which contents of vesicles or pustules were analysed, Staphylococcus aureus was the only pathogen isolated. In non-bullous variants of C.I. Staphylococcus aureus was the most often isolated organism as well. Both staphylococci and streptococci were isolated in 12 cases, whereas in just 9 cases streptococci were the only pathogen detected. All Staphylococcus aureus isolates were sensitive to flucloxacillin and cefotaxime. Erythromycin-resistance amounted to more than 20 percent. The percentage of resistant staphylococci against the predominantly topically applied antibiotics fusidinic acid and mupirocin was 2 and 0 per cent, respectively.For all manifestations of C.I. Staphylococcus aureus is at present the leading organism which has to be taken into consideration for treatment. If oral antibiotic therapy is indicated, penicillinase-stable penicillins or cephalosporins, preferably of the cefalexin-type, are the drugs of choice. Macrolides are no longer recommended for initiating of C.I. treatment.