The actual disappearance of pregnancy-related acute renal failure (PR-ARF) is a common "feeling" for nephrologists. The aim of this study was to exactly quantify this event by evaluating epidemiology and the extent of renal damage in PR-ARF. From 1958 to 1994, 84 cases of PR-ARF were observed (5.8% of total number of ARF needing dialysis). In four successive periods (1956-67, 1968-77, 1978-87, 1988-94), the incidence of PR-ARF fell from 43% to 0.5% with respect to the total number of ARF, and from 1/3000 to 1/18,000 with respect to the total number of pregnancies. Maternal mortality in the past was high (31%), but no cases of death in the last period were seen. Irreversible renal damage was recorded in 11.1% of PR-ARF, and, in particular, in 18.7% of cases of preeclampsia-eclampsia (PE-E). The worst maternal and renal prognosis occurred in PE-E that was complicated by abruptio placentae (AP). Neither disseminated intravascular coagulation (DIC), microangiopathic hemolytic anemia, nor prostacyclin imbalance were significantly related to the severity of renal damage. Heparin therapy did not modify DIC evolution and renal outcome and was aggravated by severe hemorragic complications. Support therapy with plasma infusion, antithrombin III, and antiplatelet agents seems to be helpful. In conclusion, PR-ARF has become a rare occurrence and, in our experience, no cases of death or irreversible renal damage were observed in the last 7 years. The most important reasons for this favorable evolution seem to be an improved medical care and more effective measures of careful prevention, mainly regarding tempestive delivery.