The effect on the tensile strength of healing wounds of 2 of the most commonly used antifibrinolytic substances, tranexamic acid and epsilon-aminocaproic acid, has been studied in white rats. 2 symmetrical linear lines were made on the dorsal skin, in 1 of which was injected 1 ml of the test solution. The incisions were closed with interrupted sutures, and after 7 days the animal was sacrificed, the wound excised and its tensile strength determined. The results showed tranexamic acid (1 ml of a solution containing 100 mg/ml) to have a positive effect on wound healing, whereas epsilon-aminocaproic acid (1 ml of a solution containing 400 mg/ml) had a negative effect. When both agents were compared in the same animal, wounds in tissue injected with tranexamic acid had a higher tensile strength than those made in tissue pre-treated with epsilon-aminocaproic acid. Even compared at the same ionic strength, similar results were obtained. It is clear from this investigation that, unlike epsilon-aminocaproic acid, tranexamic acid has a positive effect on wound healing, and that this effect is not due to the antifibrinolytic properties, as both are powerful fibrinolytic inhibitors.