We describe our experience of open partial nephrectomy with a parenchymal clamp, the Reni-Clamp, in 30 patients from January 2002 to May 2005. The mean operative and clamping time was 150 and 27 minutes, respectively, and the blood loss was 150 mL. The Reni-Clamp enabled us to perform partial nephrectomy safely in all cases of polar or external edge renal tumor.