The use of medicinal herbs, as substitutes for pharmaceutical intervention during pregnancy, represents a potential for lower side effects and less toxicity than currently used synthetic drugs. This study investigates the histopathological effects of barley grain on the development of the cortical portion of the adrenal glands in albino rat foetuses derived from mothers who have been rendered diabetic by streptozotocin. Sixty healthy female rats were randomly allocated into four groups. Streptozotocin was applied by intraperitoneal injection in two of these groups. After natural mating and confirmation of pregnancy, one control and one diabetic group were treated with barley grains. At day 21 of gestation, pregnant rats were anaesthetized and all foetuses were surgically removed, fixed by immersion in 10 % formal saline and subsequently histologically processed for microscopical examination. The degree of differentiation of the adrenal cortex was greater in foetuses from the diabetic groups treated with barley grains compared with those untreated. These results indicate that the use of barley grain may be appropriate to improve the development of the foetal adrenal cortex in foetuses affected by maternal diabetes.