Adrenal weight, adrenal hydroxysteroid dehydrogenase activity and serum corticosterone level were significantly higher in rats fed with 5% case in diet after 7 days of swimming stress (45 min/day) as compared to their controls. All the parameters were similar to their control levels in rats receiving 20% case in diet and exposed to swimming stress. The results suggest that case in can play an important role in preventing adrenocortical hyperactivity in swimming stressed rats.