Hirudin, a thrombin inhibitor isolated from the leech Hirudo medicinalis, has been long known for its anticoagulant effects. In 1990, the former German BGA has published a monograph on Hirudo medicinalis extract (containing Hirudin and Eglin), stating that its local use is indicated in bruises with or without hematoma. The aim of this double-blind, placebo-controlled clinical trial was to evaluate the efficacy and safety of a Hirudin-containing cream (Hirudex cream; Hirudo medicinalis extract 280 UI/100 g) in patients affected with bruises with or without hematoma. 60 men and women between the ages of 18 and 65 years with a unilateral acute musculoskeletal injury (bruise) with or without hematoma were included. Dosage schedule and application route for both treatments were the following: 3-4 daily applications for 5 days for a total of 15-20 administrations during the whole study period. In the Hirudin group, a highly statistically and clinically significant improvement were noted. Although a statistical improvement was also seen in patients treated with placebo, this was less pronounced, and a highly significant between-group difference was noted for all three major efficacy parameters at each follow-up visit in favour of Hirudin. Both the patients and the investigator considered the overall assessment of efficacy at the end of the study to be significantly better (p < 0.001) in the Hirudin group than in the placebo group. Results of this study suggest that Hirudin is an effective local treatment in patients with mild to moderate bruises.