Adult guinea pigs received intragastrically solutions of milk whey protein concentrate (CWPM), its enzymatic hydrolysate (HWPM) and peptide fraction (PF) obtained by means of HWPM ultrafiltration. Milk protein antigen content of CWPM, HWPM and PF was preliminary characterized with two-dimensional and rocket immunoelectrophoresis. Undigested beta-lactoglobulin (beta LG) absorbed from the gut, was measured three hours after the administration by means of competitive radioimmunoassay. Administration of proteins was repeated twice with daily intervals. Twenty one days later the levels of circulating anti-beta LG antibodies were measured by Farr's method and then the reaction of active anaphylactic shock was triggered by intravenous infusion of whole skimmed milk. It was established that while antigens including beta LG content decreased in the rank of CWPM-HWPM-PF the absorption of beta LG into the blood serum and the violence of acute anaphylaxis decreased also. The largest level of specific antibodies to beta LG was detected in animals that received the hydrolized protein the fact being connected with the presence of aggregated beta LG in this preparation. The employment of ultrafiltration of enzymatic hydrolyzate leads to elimination of the majority of noninactivated antigens from the filtrate, consequence of this being the low level of animal sensitization by this preparation. It has been concluded that ultrafiltration technology has good advances in manufacturing hypoallergenic milk formulae.