The effect of an electromagnetic field on the healing of skin ulcers of venous origin in humans has been investigated in a double-blind study. Forty-four patients have been admitted to the study; one-half were exposed to active stimulators (experimental group) and the remaining to dummy stimulators (control group). The stimulation was scheduled to last a maximum of 90 days. The success rate was significantly higher in the experimental group both at day 90 (p < 0.02) and in the follow-up period (p < 0.005). The data suggest that the effect of the electromagnetic field lasts even when the stimulation is over. No ulcers worsened in the experimental group, while four worsened in the control group. Twenty-five percent of the patients in the experimental group and 50% in the control group experienced recurrence of the ulcer. It is concluded that stimulation with an electromagnetic field is a useful adjunctive therapy in the management of these patients.