Twenty patients with gynaecomastia undergoing operations on 33 breasts were entered into a prospective randomised controlled clinical study. The breasts were randomised to receive nothing or adrenaline infiltration prior to mastectomy. Blood loss during surgery and drainage afterwards were compared between the two groups. Statistical analysis using the Wilcoxon rank sum test (two-tailed) showed a statistically significant reduction in operative blood loss (p less than 0.01) but no difference in postoperative drainage. There was no adverse effect on the viability of the skin flaps or the nipple-areola complex.