The changes of peculiarities thymocytes membranes after the UV actions on the suspension cells were investigated. The POL intensivity; content the carotene, vitamins A,E and its metabolites were determined. The state of membrane lipids and proteins was observed by fluorescent zondes. After 15 min of UV action form of the humoral activity products of POL was increased; the redox system of vitamin E was mobilized; the membranes proteins was opened; the neutral lipid fraction in membranes was decreased, and its polarity was increased. After 25 min of UV action was observed: the stimulation of the first and second steps of POL; decreased of AO activity; more opened of membranes proteins; more increased of polarity lipids and reform of lipofility of membranes. This changes lay in the base of activity and passivity of thymocytes by UV.