Abstract: A method is described for the diagnostic determination of the risk caused by an altered oxidative balance, comprising the photometric measurement of total cholesterol, hydroperoxides, and antioxidant capacity, on the basis of which the protective index, the oxidative index and the risk index caused by an altered oxidative balance (or ‘OBRI’) are calculated. This latter index has proved to be particularly dependable and reliable in determining the status of the oxidative balance in relation to cholesterol levels, being highly predictive of cardiovascular risk.