Myositis was produced experimentally by injecting 2 ml turpine oil in the gluteal muscles of 10 sheep. From these 10 sheep, 5 sheep (group A) were treated with diclofenac sodium @1m1/kg body weight intra muscularly for 3 consecutive days after the development of myositis. Rest 5 sheep were kept as control (group B). Moderate (++) lameness and local swelling was recorded in all sheep of group A. In treated animals of group A, lameness reduced to mild level (+) in 80% cases and became nil in 100% cases from day 2 and day 3 post treatment respectively. Control animals were recovered (100%) on 6 days post myositis. Total leukocyte count (TLC) increased significantly (p<0.05) in group A in myositic condition than in premyositis. In the treated animals of group A total leukocyte count came down (p<0.05) to premyositic level after 3 days post treatment. But in control animals of group B did not decreases significantly (p<0.05). Similar result was found in case of neutrophil count. Histopathological study showed swollen, edematous, hemorrhagic muscle fibers with neutrophilic infiltration and fibrosis replacing the dead tissue revealed in the control animals. In the treated animals of group A almost similar changes were present but more fibrosis was noted.