Henoch-Shönlein purpura (HSP) is an immunoglobulin A (IgA) vasculitis that affects the small vessels. It is a multi-organ system disease that may include cutaneous purpura, arthralgia, acute enteritis and nephritis. Nephritis is characterized by mesangial proliferation with IgA deposits. Neurological, pulmonary, cardiac or genitourinary complications occur rarely. The acute stage progresses by successive flare-ups of limited duration. Although the cause is unknown, it is clear that IgA plays a central role in the immunopathogenesis of HSP. The syndrome usually affects children in which evolution is generally favourable. In adults the disease is rare and seems different from children with much more severe manifestations and prognosis. Short-term outcome, in children as in adults, depends on the severity of gastrointestinal manifestations. Long-term outcome depends on renal involvement. In studies with enough observation time, as much as one third of the patients will progress to end stage renal failure. The benign manifestations of the disease are managed by appropriate symptomatic measures. In case of severe involvement, including severe gastrointestinal complications or proliferative glomerulonephritis, immunosuppressive drugs may be required including steroids. These specific treatments are still controversial and their efficacy has to be evaluated.