Report on three children with hydrocephalus in whom an immune complex nephritis ("shunt-nephritis") had occurred in consequence of an infected atrioventricular shunt. Besides the clinical course, the histological findings which are of particular significance with regard to pathogenesis are discussed as well as the serum complement system on the basis of the laboratory data. Removal of the valve system led to a complete normalization of the laboratory parameters and to a subsidence of the clinical symptoms in all patients. The necessity of a perioperative antibiotic prophylaxis in the insertion of an atrioventricular shunt is explicitly emphasized. Narrow-interval follow-up investigations should enable early detection of cases of shunt nephritis and thus prevent functional residues or even fatalities. Knowledge of this immune complex nephritis is also very important because it is one of the few forms of nephritis in which a causal therapy is available with removal of the infected shunt.