Adult male albino rats received 18 mg/kg i.p. of suramin twice a week, comparable to the human therapeutic situation. Sacrifices took place after 30 and 60 days of treatment. Adrenal cortex and major salivary glands were examined, using morphological and histochemical methods, in order to obtain a) confirmation of adrenocortical damage reported previously and b) original data for the major salivary glands. In rats the submaxillary gland in particular has already been found to be closely related to the functional conditions of the adrenal cortex. In all organs examined, alterations already evident in 30 day-treated rats, were constantly more marked and widespread in 60 day-treated animals. At the end of the treatment the adrenal cortex showed morphological (poor differentiation of the zona glomerulosa, hypertrophic cell clusters in the zona fasciculata) and histochemical (different distribution of neutral lipids, cholesterol and delta 5-3 beta-hydroxysteroid dehydrogenase) changes. Damage (vacuolizations, lymphocytic infiltrates) observed in major salivary glands was shown to be more marked and widespread in the submaxillary gland, confirming its functional dependence on adrenocortical activity.