Although copper is an important biological trace element required for normal metabolism, occupational exposure to copper in different industrial workers may result in abnormal rise in plasma copper level which can bring about adverse effects. Intraperitoneal injection of copper chloride at the dose of 2000 μg/kg per day and higher doses for 26 days resulted in significant rise in adrenal weight, adrenal Δ5-3β hydroxysteroid dehydrogenase (HSD) activity and serum corticosterone level in both adult and immature male rats, while 1000 μg/kg per day dose for 26 days duration did not significantly alter the adrenocortical activities and adrenal weight in adult rats. On the contrary, the latter lower dose caused a significant decrease in adrenal Δ5 3β HSD activity and serum corticosterone level in immature male rats. © 2002 Published by Elsevier Science B.V.