Objective To compare the results of single and repeated percutaneous sclerotherapy in patients with simple renal cysts .Methods 96 patients with simple renal cysts underwent needle aspiration and sclerotherapy under CT guidance. 45 patients (group A) underwent one session of sclerotherapy with 99.7% ethanol immediately after aspiration and 51 patients (group B) underwent repeated sclerotherapy at least twice. The patients were followed up using ultrasonography or CT at 3～6 months intervals. The complete or almost disappearance of the renal cyst was considered a successful treatment.Results The efficacy of treatment was significantly different in two group . The overall effective rate were 91.1% and 98.8% in group A and group B , respectively. The rate of complete regression was significantly better in group B (80.4%) than in group A (62.2%,?