Malignant nephrosclerosis is acute renal failure in the setting of malignant hypertension and may be associated with thrombotic microangiopathy. Although the prognosis has improved considerably over the past decades, renal dysfunction remains an important cause of morbidity and mortality. Adequate control of blood pressure is crucial, allows gradual healing of the necrotizing vascular lesions and may induce stabilization and improvement of renal function in about 50 - 80% of involved patients. In addition, recent investigations have provided a better understanding of the pathophysiology of malignant hypertension and offer possibilities for identifying patients at risk. We report 3 patients who developed severe acute renal failure requiring dialysis initiation in the setting of malignant hypertension. All patients had kidney biopsy proven malignant nephrosclerosis and presented with symptoms of thrombotic microangiopathy. Despite adequate blood pressure control the prognosis of our patients varied.