Low concentration of immunoglobulins G, A and M and complement component proteins were found in leg lymph of normal men. The lymph/serum ratios of different proteins ranged from 0.07 to 0.24 and depended on the molecular weight of the measured protein. Major variations in concentration were found dependent on the rate of capillary filtration and lymph formation. Hemolytic activity of total complement and of the 9 components were low, with the L/S ratio from 0.06 to 0.25. The C3H50 in lymph was much lower than of the remainder of components. Remarkably low immune adherence capacity of lymph C was noted.