BACKGROUND Rouget du porc, or swine erysipelas, usually occurs in man as Rosenbach's erysipeloid. Septicemic forms are more uncommon and can be associated with dermal involvement far from the site of inoculation. We report a case in a patient given corticosteroid therapy for systematic lupus. METHODS A 50-year-old farmer was seen with fever, infiltrative erythema of the long finger and dorsal lesions on the ring finger which developed after a skin lesions caused by a duck. The diagnosis of septicemic rouget du porc was made after isolating the germ from blood cultures. There was no associated endocarditis. Fever and skin lesions totally regressed after treatment with ceftriaxone. CONCLUSIONS The diagnosis of erysipeloid was supported by epidemiologic arguments and characteristic clinical features. The corticosteroid therapy was probably a favoring factor for development of septicemia. Positive diagnosis is usually obtained from blood culture but the germ can be isolated from skin biopsies at the site of inoculation. Our patient was free of endocarditis which should always be suspected. Endocarditis is frequent and often fatal. Intravenous high-dose penicillin G is recommanded treatment.