Although the short- and medium-term (5-10 years) outcome of patients with lupus nephritis has been studied extensively, there are very few data on the second and subsequent decades. We studied outcome in 110 local patients investigated at a single centre before 1986, who all had potential follow-up of more than 10 years (actual 2-31 years, median 15.5 years). At last follow-up, 40 patients were dead and 70 alive, nine of whom were on maintenance dialysis or transplanted, actuarial survivals being 84%, 72%, 62%, 61% and 54% at 5, 10, 15, 20 and 25 years for the group as a whole. Survival was better in the cohort 1976-86 (n = 60) than in that from 1963-75 (n = 50) (90, 81 and 76% vs. 78, 56 and 43% at 5, 10 and 15 years, p < 0.001). Sepsis (12) and myocardial infarction (8) were the principal causes of death. Of living patients with renal function, 38% had normal urine and renal function, 11 were off all treatment (19%), 62% had persistent proteinuria and 18% had reduced but generally stable renal function. Renal failure, in those patients who developed it, occurred during the first decade and none of 67 patients actually followed more than 10 years subsequently went into renal failure. Induction treatment was with prednisolone, combined with azathioprine in more severe forms of nephritis, and from the middle 1970s to 1986, 30 with methylprednisolone and in 12 cases plasma exchange. Seventeen other patients were treated using oral cyclophosphamide during the 1960s. No patient received i.v. cyclophosphamide as induction therapy, although nine patients had this form of treatment later, largely because of non-compliance. Serious complications of lupus and/or its treatment occurred in 49%: sepsis in 32, ischaemic heart disease in 20, thrombosis in one and avascular necrosis of bone in eight. In contrast, fracturing osteoporosis occurred in only three, and cataracts requiring surgery and diabetes mellitus in none. The very long-term outlook of lupus nephritis, especially its more severe forms, has improved, but that with current management strategies only a minority of patients are able to stop treatment altogether, and the incidence of serious complications is high.