Nutritional myopathy in broiler chickens is a condition that is generally asymptomatic but leads to a loss of meat quality. This condition could sometimes be associated with suboptimal or deficient levels of vitamin E (VE) in the diet. The objectives of this study were to assess the effect of extra dietary VE in a commercial diet on muscle integrity and to determine an efficient diagnostic test for early detection of muscle damage, to subsequently adjust VE levels in the diet. One-day-old male broiler chicks were randomly assigned to 2 diet treatments: a commercial diet in which up to 50 mg/kg of VE was added, or a commercial diet with no extra VE. At 28, 35, 42, and 49 d, blood samples were taken to measure plasma VE and creatine kinase (CK) activity. Both pectoralis superficialis and adductor magnus muscles were sampled for histological examination, and degenerated fibers were counted. Plasma levels of VE were higher in chickens from the test group (P = 0.001), whereas CK activity was not different between groups (P = 0.20). Less damaged fibers were also observed in the pectoral muscle at 28 d in chickens receiving the diet supplemented with extra VE. Therefore, adding VE to the conventional diet increased plasma VE and mildly decreased the number of damaged fibers in the pectoral muscle of young broilers. Blood CK activity was not a reliable biochemical indicator of mild muscle degeneration in broiler chickens.