Components of the cyclic nucleotide system--cAMP, cGMP, activities of adenylate cyclase (AC) and phosphodiesterase (PDase) were studied in brain, lung, adrenal gland, liver tissues, in blood plasma (cAMP, cGMP) and in leukocytes (AC and PDase) of guinea pigs at the periods of sensibilization and development of anaphylaxis. Dibutyryl cAMP was preadministered in a number of the animals in order to correct possible alterations in the system of cyclic nucleotides and to stimulate unspecific resistance of the organism. Distinct alterations were observed in the patterns studied after sensibilization of the animals, especially pronounced in anaphylactic shock. Preadministration of dibutyryl cAMP prevented development of anaphylactic shock in all the animals treated with the antigen. Even after repeated administration of the antigen the antigen. Even after repeated administration of the antigen the anaphylactic shock was observed only in 50% of these animals. The data obtained suggest that synthetic analogues of cAMP may be used for treatment of patients with allergic disorders.