The effect of testosterone propionate in different treatments was tested in adult male rats (250 g.) with mechanical skin experimental lesions. The whole period of cicatrization was investigated in normals, castrated and testosterone treated animals. We could not detect any alteration in the regeneration process in both treated and untreated rats (normals and castrated). Diffusing factor obtained from homologous testis, directly applied upon the lesions also do not change the healing period. Related to the course of the healing process, little evidence is presented by variance analysis that significative differences could be detected in the first periods, in both castrated and testosterone treated groups; however new well planed experiments should be carried to test this point.