In the period 1968-76, necropsies were carried out on 30 patients who had been treated by long-term intermittent maintenance haemodialysis. Fourteen of these patients developed bilateral cystic disease of the kidney. Clinical, pathological, and radiological investigation of these patients when they first presented did not reveal any evidence of renal cystic change. The main complications of this condition are haemorrhage and tumour formation. Six patients developed renal tumours, and in five cases these were multiple. The histological appearance of these neoplasms gave no indication as to whether they would behave in an aggressive manner. One patient died of metastatic carcinomatosis from a renal primary. The condition of acquired cystic disease of the kidney should be suspected if patients on maintenance haemodialysis suffer from recurrent haematuria or are found to have enlarging kidneys.