Aim. To assess the long term outcome of patients with IgA nephropathy. Method. The outcome of 151 patients (120 male; mean age 32.5, median age 29.6, SD 15.4 years; 146 Caucasian) with biopsy-proven IgA nephropathy. The patients were enrolled between 30 April 1973 and 21 August 1992. Results. Ninety-five (63%) of the patients presented with microscopic haematuria, with or without proteinuria and/or renal insufficiency. At presentation renal insufficiency was present in 34% and hypertension in 48% of patients. During a mean follow up period of 63.3 months (range 0-233 months) 12 patients have reached end stage renal failure, five have died of a nonrenal cause and 25 were lost to follow up. The actuarial renal survival rate was 92.6% at five years and 91.1% at both 10 and 15 years. A significantly poorer renal survival rate was seen in those patients with a plasma creatinine greater-than-or-equal-to 0.12 mmol/L, hypertension, a serum albumin of <35 g/L, or a 24 hour urinary albumin excretion greater-than-or-equal-to 1.0 g at presentation, and this became apparent within the first few years of follow up. Conclusions. The long term outcome of IgA nephropathy is better than previously reported. Those patients with a poor prognosis can be identified with considerable certainty at presentation.