The study was conducted on fifteen 16-month Leghorn hens raised in cages under standard feeding conditions and lighting 14L:10D (light from 7.00 to 21.00). The control group comprised hens that did not undergo any procedure, the second control group underwent a mock operation, while the experimental group was subjected to pinealectomy. The procedures were carried out under general anesthesia. Oxygen consumption was measured and rectal temperature recorded during the light (10.00-15.00 h) and dark (22.00 -3.00 h) periods of the day. Feed intake was recorded for the periods between 7.00-15.00 and 15.00-7.00 h. It was found that pinealectomy significantly increased nocturnal oxygen consumption and rectal temperature. Pinealectomized hens consumed considerably more feed during the day, particularly in the afternoon and at night. These results show that pinealectomy in adult hens modifies circadian metabolic rate and feed intake.