Abstract: The effects of zinc deficiency on the serum cortisol and adrenocorticotrophic hormone (ACTH) concentration,and the cerebrum nitric oxide synthase (NOS) activity in rats were studied.Growing rats were allotted to three groups,which were zinc deficiency (ZD),paired-fed (PF) and zinc supplementation after feeding zinc deficient food for 21 days (ZS).The duration of feed test was 35 days.Compared with PF rats,serum cortisol concentration in ZD ones was significantly increased,whereas serum ACTH concentration and cerebrum NOS activity were significantly decreased.The results suggested that zinc might influence the metabolism of hypothalamichypophysial-adrenocortical axis and NOS.