A retrospective study was carried out on 219 patients who underwent surgical treatment of a malignant melanoma. A scalpel was used in 96 patients in group 1 and CO2 laser beam was used in 123 patients in group 2. The average length of hospitalization for group 2 was longer (16.3 versus 12.8 days for group 1). This was due to failure of the skin graft; 32.5 per cent in group 2 versus 15.6 per cent in group 1 (p = 0.005). The accumulative rate of recurrence for both groups was almost the same although there were significant differences according to the various parameters. Male patients in group 2 had a significantly higher rate of recurrence as compared with female patients in the same group (p less than 0.001) and male patients in group 1 (p = 0.002). In both groups, there was a significantly higher rate of recurrence for ulcerated primary lesions and those lesions more than 1.6 millimeters thick (p = 0.05). Patients in group 2, with lesions more than 3 millimeters in thickness, had a higher rate of recurrence than those in group 1 (54.6 versus 40.6 per cent). In both groups, patients who underwent elective regional dissection of lymph nodes had a lower rate of recurrence (19.4 per cent) than those patients who did not undergo dissection (53.6 per cent) (p = 0.001). It is suggested that thermal damage to the blood and lymph vessels incurred during laser excision may be more extensive than has been reported. These damaged walls may cause the higher rate of distal metastases of malignant melanoma from a primary lesion more than 1.6 millimeters in thickness; primarily in male patients.