Glycerol, alpha-carotene, and other yet unidentified compounds have been found in the ethanol extract from winter caterpillars of the black-veined white (Aporia crataegi L.). We have shown that the ethanol extract has a cryoprotective effect on human peripheral blood lymphocytes, and this activity is approximately three times higher than that of glycerol (particularly, in the case of repeated freezing), which is one of the best cryoprotectors.