Studies of incisional wounds in young (2.5-3.0 months) and old (18-23 months) rats were undertaken at days 8 and 21 of healing. Load-deformation diagrams were obtained from standardized strip specimens of the wounds, and several parameters were assessed from these curves. The morphological changes in the wounds during mechanical straining were studied by incidental light microscopy. The wounds in young rats had better mechanical properties, i.e. greater strength, elastic stiffness and energy absorption, than those in old rats. The morphological analysis demonstrated that at 21 days of healing the wounds from young rats displayed a more complex and organized fibre arrangement than the wounds from old rats. These findings indicate that the faster healing observed in young rats is, at least to some extent, due to a better organization of the collagenous fibre meshwork.