Univariate survivorship analysis of a cohort of 365 patients with idiopathic IgA mesangial nephropathy and at least one year of further observation since the apparent onset (mean = 7.79 +/- 6.19 years; median = 6.16 years) has been performed. Observations for at least one year (mean = 5.05 +/- 3.66; median = 4.08 years) after biopsy was available for 292 of these. One immunohistological, four clinical, and six histological features were associated with increased risk of developing renal failure: (i) older at onset; (ii) no history of recurrent macroscopic haematuria; (iii) proteinuria of more than 1 g/day; (iv) arterial hypertension at the time of biopsy; (v) extent of glomerular obsolescence; (vi) extent of segmental glomerulosclerosis; (vii) presence of interstitial fibrosis; (vii) presence of diffuse intracapillary proliferation; (ix) presence of extracapillary proliferation; (x) presence of segmental thickening of glomerular basement membrane; (xi) extension of IgA deposits to the peripheral capillary loops shown by immunofluorescence. Only features (iii), (v), (vii) and (xi) proved to be independent prognostic indicators in the multivariate survivorship analysis (Cox regression model).