In experiments on mice and the influence in vitro of the dipeptides GluTrp, LysAsp, LysVal, AspGlu, GluAsp on their constituent amino acids and mixtures on the indexes of specific and non-specific resistance was studied. There is no difference between the dipeptides and their constituent amino acids (excepting Lys) neither in immune, phagocytosis modulating or antitoxic properties. Some amino acids (aspartic acid, glutamic acid, methionine and tryptophan) are promising for the effective prevention of diseases that develop as a result of chronic benzene intoxication.