The ability of aluminium phosphate and calcium phosphate to stimulate the synthesis of tetanus toxoid-specific anaphilactic and antitoxic antibodies is compared. The observed differences in the kinetics of IgG1a, IgG1b and antitoxines are quantitative--titres after application of aluminium phosphate are higher. Booster immunization with aluminium but not calcium phosphate-adsorbed toxoid leads to a prolonged synthesis of specific IgE. It is hypothesized that the regular application of aluminium compound-containing vaccines on the entire population could be one of the factors leading to the observed increase of allergic diseases.