The behavior of the occipital alpha rhythm during open-eye derivation was studied on nine- to twelve-year-old boys of normal intelligence, of whom ten were free from brain injuries and eleven had been suffering from brain injuries in early childhood. 2. There was observed a marked tendency of the alpha index to differ in dependence upon the time of testing, the cause of which was believed to be a weakness of vigilance on the part of brain-injured children. 3. Application of this simple method of examination to group comparisons makes it possible to neurophysiologically determine an important part of chronic cerebropsychic axis syndromes.