Skeletal muscle injury which comprises, a high proportion of sport injury, is associated with inflammation, transudation and fibrin deposition (Murray - Leslie, 1986). The injured muscle fibres, when relatively small, have the capacity for regeneration and repair and are again capable of contraction. With larger injury and/or presence of systemic diseases, there is a reduced capacity for regeneration and repair and the muscle fibers can ultimately be replaced by fat and/or fibrous tissue (Ambrosia, 1986}. A modality able to enhance healing of such injury may facilitate restoration of the prior level of function. Low dose pulsed ultrasonic therapy was proved to be more effective than radiant heat, short-wave diathermy or paraffin baths in helping patients with sprained ankles to return to work (Middlemast,1978).Various other researches including topics as surgical wounds, varicose ulcers and pressure sores, were in favor of the healing effect of pulsed ultrasound and support such an idea (McDiarmid et al.,1985 and Hong et al., 1988). Pulsed ultrasound can be applied safly during the early stages of healing without fear of bleeding due to its minimal thermal effect in comparison with the non thermal one (Dyson & Suckling, 1978; Partridge, 1987 and Lehman & DeLa-teur, 1989). Other contradictory results proved that low dosage of pulsed ultrasound impair healing when applied on freshly healing tendons in rabbits (Roberts, 1982). Despite these numerous experiments and the importance of early recovery after skeletal muscle injury,