Cadmium-induced stress adversely affects testicular activity and causes sympathetic stimulation. To investigate the effect of atenolol, a beta-adrenergic receptor blocker, on testicular androgen synthesis after cadmium treatment, adult Sprague-Dawley strain male rats were given a single sc dose of cadmium chloride 0.45 mg/kg BW. Animals were killed on day 3 after treatment. Adrenal weight, adrenal delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) activity, serum corticosterone, and brain noradrenaline were increased significantly while testicular delta 5-3 beta-HSD and 17 beta-HSD activities, serum testosterone, and accessory sex organs weight were decreased. Oral coadministration of atenolol at a dose of 2.0 mg/kg body weight for 3 days resulted in complete protection of adrenal delta 5-3 beta-HSD, testicular delta 5-3 beta-HSD, and 17 beta-HSD activities, adrenal weight, serum corticosterone, and serum testosterone when compared with cadmium-only group and there were no significant differences in these parameters from the vehicle control values. Simultaneous administration of cadmium and atenolol also protected brain noradrenaline content and reduced the rise of testicular cadmium concentration. All the parameters were similar to control levels in rats treated with atenolol alone. We conclude that atenolol may protect testicular androgen synthesis by inhibiting the action of noradrenaline on testicular Leydig cells and adrenocortical hyperactivity in cadmium-treated rats.