In the present investigation, the hemolytic properties of T-2 toxin were examined. Tests with different concentrations of T-2 toxin showed that essentially complete hemolysis of rat erythrocytes commenced after a lag period, the length of which depended on the concentration of toxin. Comparison of the characteristics of hemolysis caused by T-2 toxin, saponins, H2O2, and polyoxyethylene surfactants showed great similarity between T-2 toxin and the latter two which proceed by a free radical mechanism. The same mechanism was suggested for hemolysis caused by T-2 toxin on the basis of the additional following observations: (1) darkness inhibited hemolysis; (2) specific free radical scavengers, i.e., vitamin E, mannitol, and histidine, inhibited hemolysis caused by T-2 toxin.