Acute enzootic muscular dystrophy of adult lambs due to vitamin E and/or selenium deficiency was suspected in local adult lambs of Basrah, Iraq. The study was conducted on 82 adults local breed lambs 8-11 months of age. Suspected animals show panting with increase abdominal respiration and mouth breathing, recumbence and unable to stand with acute death within 24-48 h. Fifteen clinically healthy lambs were considered as controls. The hematological changes indicated a significant decrease in RBC, Hb, and PCV reflected macrocytic hypochromic type of anemia. Indices of clotting factors show significant changes in diseased adult lambs. Results of the biochemical changes indicated a significant decrease of vitamin E, and the glutathione peroxidase, in diseased animals, whereas, a significant increase indicated in the values of AST, CK and troponin I. Results of the post-mortem examinations showed enlargement of the heart with a white-colored irregular patch. Furthermore, results of histopathological changes indicated an acute cellular degeneration of myocardial fibers associated with diffuse interstitial edematous fluid in the myocardial parenchyma and acute cellular degenerative myocardial fibers with a marked degree of degeneration in the myocardial parenchyma. It has been concluded that, acute enzootic muscular dystrophy has an adverse harmful clinical effect on adult diseased lambs which could always be terminated with death.