In this prospective randomized study we have compared argon-enhanced electrosurgery with conventional diathermy in a consecutive series of 50 patients undergoing mastectomy. The groups were comparable in age, menopausal status, tumour size, stage and specimen size. Patients undergoing mastectomy using argon diathermy had significantly less blood loss intraoperatively (521 (67)ml vs 824 (59)ml; P<0.001) and a significantly lower transfusion requirement postoperatively. There were no significant differences in post-operative drainage (1350 (160 mi vs 1527 (169) mi; P=NS), length of hospital stay, incidence of seromas or other complications. Argon diathermy significantly reduces intraoperative blood loss and should be considered as the method of choice in patients undergoing mastectomy.