A total of 109 subjects aged 60 years or more and without any focalized cerebral lesions were studied by E.E.G. and C.T. scan recordings. An original type of planimetric study of the C.T. scan sections was used to obtain numerical ratios of the degree of cerebral atrophy. The planimetric ratios and the E.E.G. data were then studied as a function of age-group and clinical condition. Most of the data obtained was then treated in a computer. Ventricular dilatation is a constant and progressive feature of normal aging, and is therefore correlated with its, whereas it cannot be significantly correlated with senility changes. The E.E.G. shows no precise correlation with age during normal aging but reflects the functional disturbances of senility disorders, especially dementias. There is no correlation between the E.E.G. and C.T. scan results either during normal or pathological aging.