Rhabdomyolysis is a rare perioperative complication, however, potentially lead to fatal outcome. We experienced 2 cases of rhabdomyolysis after radical nephrectomy and nephroureterectomy in the lateral decubitus position. (Case 1) A 40-years old man was seen in our hospital because of asymptomatic grosshematuria. Computed tomography revealed right renal pelvic cancer, cT3N0M0. Right radical nephroureterectomy, lymph node dissection, partial cystectomy was underwent, and the operation was finished without any trouble. At the post-operative day 1, serum creatinine level was elevated to the point of 4.2 mg/dl, and serum creatine kinase was 1,945 IU/l. Continuous hemodiafiltration (CHDF) was done at intensive-care unit (ICU), and serum creatinine and creatine kinase level were decreased. At the post-operative day 1, urine myoglobin level was prominently elevated (2,943.7 ng/ml), so we diagnosed acute renal failure due to rhabdomyolysis. (Case 2) A 40-years old man was incidentally pointed out of right renal tumor that was seen as renal cell carcinoma, cT1aN0M0. Open partial nephrectomy was underwent, and there was no trouble during the operation. After recovering from anesthesia, the patient felt left thigh pain strongly. Serum creatine kinase was 888 IU/L after the operation. At the postoperative day 1, serum creatine kinase level was markedly increased (31,138 IU/L). Serum creatinine level was 1.34 mg/dl. Urine and serum myoglobin level was prominently elevated (89,000 ng/ml and 8,634 ng/ml, respectively). We diagnosed it rhabdomyolysis, and he received large amount of fluid intravenously at intensive-care unit. Serum creatine kinase was peak out at the post-operative day 3 (20,709 IU/L), and hemodialysis was not performed.