A considerable part of the paraspecific effect of immunization falls under the common term of a general increase in resistance. Bacterial competition, antibiosis, interference, interferon formation and lymphocyte stimulation, on the other hand, are more than an increase in resistance. It is proposed that the sum of the stimulation of all these activities including increased resistance shall be called premunization and the short-lasting nonspecific protection against a number of quite different infectious diseases produced by this in the body shall be called premunity. Experience with the paraspecific effect of immunizations, with increasing drug resistance, interferonization and lymphocyte stimulation form the basis for the development of a "premunity inducer". The efficacy of a biological inducer is described with reference to our own experiments.