Male offspring of neonatally vitamin A or D treated (hormonally imprinted) rat dams were studied for hormone (adrenocorticotrophine [ACTH], beta-endorphin, histamine, triiodothyronine [T-3]) content in immune cells, by using immunocytochemical methods for flow cytometry and confocal microscopy. ACTH and T-3 were almost doubled in the lymphocytes of vitamin A treated mothers' offspring, while histamine decreased to a one-third in the histamine content of vitamin D treated mothers' offspring. Part of the animals received vitamin treatment again 24 hours before measurement, however, only endorphin content elevated moderately. In the offspring of untreated dams administered with vitamin D 24 hours before measurement, each cell type studied (lymphocyte, monocyte-granulocyte group, mast cell) had a one-third lower T-3 content, which shows that vitamin D treatment can influence hormone content of immune cells. The experiments call attention to the transgenerational effect of perinatal treatment with lipid-soluble, intracellular receptor-bound vitamins.