Calves were subjected to experimental hypoxia from 0.5 to 4 h after birth. The plasma level of immunoreactive gastric inhibitory polypeptide was higher (P less than 0.05) than in control calves during hypoxia and 2 and 7 h later. However, the gastrin level was not lower during treatment and was higher (P less than 0.05) 3, 6, and 13 h later. Hypoxia could have changed circulating levels or degradation rates of these peptides and could have delayed abomasal emptying.