The study was established to compare the effects of laser, ultrasound and electrical stimulation on the healing of the Achilles tendon injury. Twenty-eight rats underwent suture repair of a tenotomy of the left Achilles tendon. The animals were randomly separated into four groups of seven animals each as follows: control group, laser group, ultrasound group, and electrical stimulation group. Following sacrifice at 14th, 23rd and 34th days, postoperatively, the retrieved tendons were quantitatively evaluated by histological techniques. The increase in the number of capillaries in the 14th day after injury and the increase of the number of fibroblasts in the 23rd day after injury suggest that the electrical stimulation accelerates collagen synthesis. At the early stages of tissue repair and considering the doses which were used, the electrical stimulation showed more increase in capillaries and fibroblasts number than the other agents for the tendon tissue healing.