The effect of mercuric chloride at two different doses, 0.5 mg/kg body weight (low dose), 1 mg/kg body weight (high dose), for 30 days, was seen on the circulating hormones in the mature male albino rats. Testosterone level was markedly decreased in the low dose (P < 0.01) and high dose (P < 0.001) treated animals. The level of luteinizing hormone (LH) was also reduced in the low dose (P < 0.01) as well as in the high dose (P < 0.001) treated animals. However, follicle stimulating hormone (FSH) and prolactin (PRL) levels were found to be decreased only in the high dose (P < 0. 05) treated animals and no change was observed in the low dose treated animals. The changes in the hormone levels caused by the mercuric chloride treatment suggest the dysfunction of pituitary-testicular axis.