In this retrospective non-randomized study we reviewed the outcome for 41 patients with membranous nephropathy older than 65 years at onset and followed for at least 1 year. Twelve of the patients never received any specific treatment (group A), 15 were treated with a 6-month course of methylprednisolone alternated to chlorambucil every other month (group B), and 14 received corticosteroids alone for 3-12 months (group C). At the end of a mean follow-up of 92 +/- 61 months in group A, 53 +/- 35 in group B, and 38 +/- 25 in group C there were significantly more remissions of nephrotic syndrome in group B than in group A (P = 0.035) or in group C (P = 0.010). Moreover patients in group B spent a significantly longer period without nephrotic syndrome than patients in group A (P = 0.000) and C (P = 0.000). Three patients in group A and one in group B died. During the follow-up six patients of group A, two of group B, and five of group C developed renal function deterioration. In patients followed for at least 5 years the mean plasma creatinine increased from a basal of 112 +/- 29 to 239 +/- 287 mumol/l at the 5th year in group A and from 113 +/- 14 to 124 +/- 30 mumol/l in group B. The mean urine protein excretion remained unchanged in group A (basal 4.6 +/- 2.3 versus 4.8 +/- 5.7 g/day at 5 years) while it decreased in group B (from a basal of 6.8 +/- 3.5 to 1.1 +/- 0.4 g/day at 5 years).(ABSTRACT TRUNCATED AT 250 WORDS)