During a 16-year period, 49 children were treated for Wilms' tumor (WT); 7 were bilateral, 5 synchronous and 2 metachronous. The age at primary diagnosis was 6 months to 5 years (mean 2.4 years). All but 1 child received preoperative chemotherapy with tumor reduction. Unilateral nephrectomy was performed in 2 metachronous cases. In 3 synchronous WTs, the tumor was enucleated in 5 kidneys and a heminephrectomy was performed in 1 kidney with a double pelvis. Two children were not operated upon. At relapse in the contralateral kidney the tumor was enucleated. Three patients died of WT, 1 is alive with disease, and 3 are without evidence of disease. Renal salvage procedures were technically feasible without complications and are advocated to preserve renal function.