In the present study 70 Streptoccus porcinus isolates could be identified and further characterized by cultural and biochemical properties, by determination of their antibiotic susceptibility and by serological classifications. The S. porcinus included serogroup-and serotype-reference strains, presumptive group candidates and isolates obtained from routine diagnostics. All cultures investigated appeared with a broad zone of beta-haemolysis on sheep blood agar showed a CAMP-like reactivity in the zone of staphylococcal beta-lysin and had the typical biochemical properties of this species. Determination of antibiotic susceptibility revealed a high number of cultures to be susceptible to ampicillin, bacitracin, chloramphenicol, penicillin and vancomycin. Resistances could be observed for erythromycin, minocycline, sulfamethoxazol-tri-methoprim, streptomycin and tetracycline.