A 29-year-old man developed acute oliguric renal failure with severe hypertension and microangiopathy. He was treated with hemodalvsis and anti-hypertensive drugs, but oliguria was prolonged. A renal biopv was performed on the 29th hospital day. Small arteries and arterioles were characterized by marked intimal thickening, and most of the glomeruli showed ischemic changes. Although there was extensive tubular loss and atrophy, regenerative changes were occasionally observed in some tubules, in which 90-kDa heat-shock protein was induced. He was diagnosed as having malignant nephrosclerosis, and was treated with a prostaglandin I₂ analog, in addition to anti-hypertensive drugs. Thereafter, his renal function recovered gradually, and hemodialysis was discontinued on the 45^th hospital day. Functional recovery lasts more than five years. We suggest that the expression of HSP90 in regenerative tubular cells is a useful histological indicator for predicting recovery from acute oliguric renal failure due to malignant hypertension.