Fifty five patients with cerebral and hypophyseal nanism and Shereshevsky-Turner syndrome were examined for toxoplasmosis. The diagnosis of toxoplasmosis was established on the basis of epidemiological and obstetrical anamnesis, clinical and roentgenological data and serological tests (complement fixation test in 2 modifications--by common and droplet method; precipitation test, fluorescent antibody test) and intradermal allergic test with toxoplasmin (ATT). Of 48 patients with cerebral and hypophyseal nanism ATT proved to be positive in 17 (35.4 per cent); it was positive in 3 of 7 patients with Shereshevsky-Turner syndrome. In some of the patients and their mothers serological tests for toxoplasmosis were also positive. Thus, toxoplasmosis infection among the patients examined was 2.5-3 times more incident than the corresponding indices in healthy children. It is supposed that there is pathology of hypothalamic regulation of hypophyseal functions in toxoplasmosis and nanism. A possibility of pathology of the generative apparatus in maternal toxoplasmosis leading to development of chromosomal embryopathies could not be excluded. The authors consider that further studies are necessary for ascertaining (in some of the cases) of the pathogenetic association between toxoplasmosis and growth and developmental disturbances.