The members of a family of four persons suffered acute gastroenteritis after eating a meal consisting of chicken. While three of them recovered rapidly, the 18-year old son developed an acute abdomen which had to be treated surgically and led to a complicated stay at the intensive care unit. Intraoperatively, a mild insignificantly inflamed appendix and an obscure segmental inflammatory process of the small bowel with local peritonitis were seen; this required an appendectomy and a peritoneal lavage. The development of bacterial peritonitis with multiple organ dysfunction required several surgical revisions with an open abdominal toilet treatment. Histological examination of the resected appendix specimen showed a severe primary fibrinoid necrotizing vasculitis with epitheloid-granulomatous reaction. Diseases such as Panenteritis nodosa, Wegener's disease and Churg-Strauss's syndrome were excluded by negative serology. By a process of exclusion, a hypersensitivity vasculitis was diagnosed and treated successfully with a high-dose cortisone regime.