A 37-year-old man undertook preoperative examination for donor nephrectomy for living kidney transplantation. Computerized tomography revealed a small renal mass (1.9 cm in diameter) with contrast enhancement on his left kidney. We couldn't exclude malignant potential for the small mass. Laparoscopic left partial nephrectomy without renal artery clamp was successfully carried out to obtain pathologic diagnosis while preserving his renal function and priority as a donor. He was judged to be an inappropriate donor candidate owing to the histopathologic report suggesting clear cell carcinoma. The patient has been followed for 27 months without any evidence of recurrence.