Thirty-two partial nephrectomies were performed without renal cooling on 13 pigs with a contact fibre Nd:YAG laser (10 W) or a steel scalpel with or without a vascular pedicle clamp. Nine pigs had a 2-week follow-up with an abdominal ultrasound 1 week postoperatively. The time for haemostasis was 6.9 +/- 5.2 min (mean +/- SD) with the laser and 9.1 +/- 5.8 min with the steel scalpel when the clamp was used (P = 0.028). There was no significant difference in the total operating time (13.2 +/- 4.5 min with the laser vs 12.6 +/- 4.6 min with the steel scalpel, P = 0.203). Intraoperative blood loss was similar in the two groups when the clamp was used. Clamping the renal pedicle decreased the blood loss by 61% in the laser group and 31% in the steel scalpel group. The number of ligatures used was significantly lower in the laser group (3.7 +/- 2.6) compared with the steel scalpel group (6.6 +/- 3.4) (P = 0.013). Five urinomas developed on the laser side and four on the steel scalpel side. These results indicate that the contact fibre Nd:YAG laser method can be used in partial nephrectomy, but it offers no definitive advantage over the conventional technique.