Henoch-Schönlein Purpura nephritis (HSPN) has been extensively studied in children but, its natural history in adults is much less known. A cohort of 250 adults suffering HSP was retrospectively analyzed for a median follow-up period of 14.8 yr. All patients had biopsies consistent with HSP (predominant IgA mesangial deposits) associated with purpura, bowel angina, and/or abdominal pain. At presentation, palpable purpura was present in 96% of patients, and arthritis was reported in 61%, and gastrointestinal involvement in 48%. Thirty-two percent of the patients showed renal insufficiency (Creatinine clearance [CrCl] <50 ml/min), usually associated with proteinuria (99%) and/or hematuria (93%). Endocapillary glomerulonephritis was the most frequent lesion on renal biopsy (61%). At the end of follow-up, patient survival was only 74%. The first cause of death was carcinoma (most of them of respiratory or digestive tract). Regarding renal function, 11% of patients reached end-stage renal failure, 13% exhibited severe renal failure (CrCl <30 ml/min), and 14% moderate renal insufficiency (CrCl <50 ml/min). Clinical remission defined as the absence of proteinuria, hematuria, and a normal renal function was achieved in only 20%. This is a retrospective study; therefore, it is not possible to demonstrate any steroid and/or cyclophosphamide efficacy in diminishing the incidence of renal insufficiency. Multivariate analysis demonstrated that renal function impairment and proteinuria level at presentation and, on renal biopsy, the degree of interstitial fibrosis, percentage of sclerotic glomeruli, and presence of glomeruli with fibrinoid necrosis were associated with a poor renal prognosis. The data indicate that clinical presentation of HSPN in adults is severe and its outcome relatively poor, worse than in children. Identification of clinical and histologic prognostic factors may permit the design of appropriate therapeutic prospective studies.