Malignant tumors of renal parenchyma remain a problem for a clinician in view of the lacking distinctive algorithm and treatment policy based principally on the diagnosis terms. Optimal treatment, surgical, is represented by two kinds of operations: preserving and radical. Out of 292 patients admitted to the clinic from 1974 to 1990, 243 (83%) underwent surgery which was conservative in 37 (15.2%) cases. Five-year survival of surgical cases was 65.5%, in nonsurgical ones 7%. The stage of renal cancer was diagnosed as I. Renal resection was universal. There were 2 cases of heminephrectomy for cancer of the fused kidney. Histologically, the tumors appeared hypernephroid carcinoma. One patient was followed up for 10 years, 11 for 5 years. Recurrences occurred in 3 cases only, massive metastasizing in 5 years in 1 case. Dysfunctions of the kidney indicate inadequacy of the organ-preserving surgery while hypofunction of the contralateral kidney suggests possibility of the organ preservation. When it is feasible technically, the residual part of the parenchyma is functionally capable and the pelviureteral system is effective, resection of the kidney is recommended even in intact contralateral kidney. Such intervention is no less radical than nephrectomy.