Pericapillary fibrin cuffs have been shown in patients with chronic venous insufficiency. It has been suggested that this fibrin deposition is responsible for an oxygen diffusion block, leading to local hypoxia and resulting in ulceration. Fibrinolysis is depressed in patients with venous insufficiency and therefore pharmacological enhancement of this factor might be expected to produce clinical improvement in this condition. Sixty patients with lipodermatoscelerosis were entered into a prospective, double-blind, placebo-controlled, randomized trial. Stanozolol 5 mg or a placebo tablet was given twice daily for 6 months. All patients were supplied with below knee German/Swiss specification class 2 graduated compression stockings. The area of lipodermatosclerosis was measured at monthly intervals and transcutaneous oxygen tension within the liposclerotic area was measured at 3-monthly intervals. The control group showed a mean reduction in area of lipodermatosclerosis of 14% (95% c.i.: -2.6-31%) compared with a 28% reduction in area in the active treatment group (95% c.i.: 5.3-46%). Transcutaneous oxygen measurements showed no change in either group. Side effects were significantly more common in the active treatment group (P less than 0.02, Chi-squared). Although fibrinolytic enhancement caused a reduction in area of lipodermatosclerosis, no evidence of any effect on a possible oxygen diffusion block was indicated.