Selenium level, and Ihe activity of GSH-Px, AST, CK, LDH and its isoenzymes were estimated in 30 lambs suspected of having the subclinical form of nutritional muscular dystrophy (NMD) and in 30 healthy lambs. A significant Se deficiency, a reduction in the activity of peroxidase glutathione, an increase in creatine kinase, aspartate aminotransferase and lactate dehydrogenase activities were found in the unhealthy lambs. Isoenzymatic profile of LDH showed 5 tractions. Tń the unhealthy lambs, there was a significant increase in LDH5 fraction-muscular isoenzyme, which is specific to the skeletal muscle. These indicators however, remained within a normal physiological range in the healthy lambs.