Ten black patients (eight men) with renal shutdown from accelerated hypertension were treated with hemodialysis. Renal function improved, and dialysis was discontinued after 6 +/- 2 months. Five patients (Group I) have maintained good renal function at 25 +/- 3 months of follow-up, whereas the other five (Group II) had deterioration again to advanced azotemia over 16 +/- 6 months. On admission, Group I patients had lower levels of serum creatinine (9 +/- 1.2 mg/dl [mean +/- SE] versus 13.6 +/- 1.7 mg/dl, p = 0.04) and urinary protein (0.98 +/- 0.78 g per day versus 2.17 +/- 1.5 g per day) and were more oliguric (451 +/- 145 ml per day versus 1,122 +/- 494 ml per day) than Group II. In Group I, renal shutdown was faster (8 +/- 4 days versus 38 +/- 28 days), recovery earlier (4 +/- 1.5 months versus 8 +/- 4 months) and greater (lowest serum creatinine level 1.9 +/- 0.3 mg/dl versus 5.7 +/- 1.7 mg/dl, p less than 0.05), and compliance better than in Group II. Two patients in the former group but none in the latter had peripheral schistocytes. It is concluded that the sustained recovery in Group I resulted from the resolution not only of the acute vascular lesions but also of tubular necrosis and microangiopathy, and the postrecovery deterioration in Group II is attributed to the more severe renal damage initially, the progression of the chronic vascular lesions in uncompliant patients, and possibly hyperfiltration damage in the remaining nephrons.