This project proposes the use of polarized currents to increase the speed of healing in chronic ulcers and donor sites in burn patients. Will be included 30 patients with chronic ulcers and 30 burn patients undergoing skin graft surgery, will be randomized into control and treated groups. For the ulcer chronic group treatment will be with 50 minutes high voltage and 10 minutes diadynamica current and the burn group only 50 minutes high voltage current.