Abstract Background/Purpose We evaluated the impact of a surgeon's experience, divided our first 20 consecutive series that involved a single surgeon at the numerical midpoint of his experience, and compared outcomes regarding this midpoint. Methods From August 1996 to August 2001, laparoscopic nephrectomy or nephroureterectomy was performed in 20 consecutive children, 12 girls and 8 boys aged between 1 and 15 years (median, 5.9 years). Disease was in the right side in 11 patients and in the left side in 9. The children were divided into 2 groups of 10. We retrospectively obtained data on all patients and compared pertinent perioperative information including operation time, blood loss, length of hospital stay, and postoperative complications. Results The procedure was feasible in all cases and did not require conversion to open surgery or perioperative transfusion in any case. The operation time reduced from a median of 181 minutes over the first 10 patients to 125 minutes over the second 10, and this difference was significant ( P = .02). Estimated blood loss and days to the first postoperative oral feeding for the second 10 patients were less than for those of the first 10 but there was no significant difference. The median hospital stay of the first 10 patients was 5.4 days (range, 2-10 days), significantly longer than the 2.5 days of the second 10 (range, 2-7 days) ( P = .009). Conclusions Laparoscopic nephrectomy operation times in children reduced when the surgical experience level exceeded approximately 10 cases.