The tissue irritating effect of a new local anaesthetic of anilide type (L67) in rat was judged from the tensile strength of healing wounds in tissue infiltrated with 0.5 ml of the solution.A 2% L 67 solution decreased the tensile strength by about 40% and a 3% L 67 solution by 56.7%.When a 2% L 67 solution and a 2% lidocaine solution were used the result showed that the lidocaine solution decreased the tensile strength by 21.8% compared to the L 67 solution.A comparison between a 2% lidocaine-epinephrine solution and a 3% L 67 solution with epinephrine 3.33%μg/ml showed that the tensile strength decreased with 31.6% in wounds inflicted in tissues infiltrated with 2% lidocaine-epinephrine solution. A comparison between L 67 and mepivacaine showed practically no difference in their effect on the tensile strength of the wounds.