Two flocks of commercial meat chickens, at 6-weeks of age, exhibited ataxia and inco-ordination progressing to complete inability to sit up or walk about. Heavy mortality occurred in both flocks due to trampling and suffocation. Gross lessions of myopathy were present in adductor and sartorius muscles. Histological examination of thigh muscles and myocardium showed the lesions to be consistent with vitamin E and/or selenium deficiency in chickens. The cause of this problem was thought to be the inclusion of poultry-offal meal in the diets.