Shönlein-Henoch's purpura (SHP) is a form of generalized vasculitis. SHP is characterized by a haemorrhagic eruption, colicky abdominal pain, renal involvement with haematuria and proteinuria, arthralgia and cerebral symptoms in the form of headache and seizures. Retrospective investigations have revealed that infection with microorganisms may precipitate SHP. The authors were able to support this observation by means of a prospective investigation. 2/3 of the 26 children in the investigation had symptoms of infection one to two weeks prior to the onset of symptoms of SHP. Ten children had definite positive signs of prior infection. The course of the sedimentation rate and leukocyte counts also support the assumption of previous infection.