Mammals show increased plasma and local (gastrointestinal tract) concentrations of some immunoregulatory hormones, such as corticosterone and melatonin, during the postprandial period. However, little is known about the endocrine and innate immune modulation in the absorptive period of ectothermic animals. This study aimed to investigate the effects of feeding on endocrine and innate immune responses in the Bullfrog (Lithobates catesbeianus). Adult males were divided in two groups: fasted and fed with fish feed (5% of their body masses). Blood and gastrointestinal tract tissues (stomach and intestine) were collected 6, 24, 48, 96 e 168 hours after feeding for measurement of neutrophil/lymphocyte ratio, plasma bacterial killing ability, corticosterone and plasma melatonin; and stomach and intestine melatonin. Feeding increased neutrophil/lymphocyte ratio at 6 h, 24 h and 96 h; and plasma corticosterone at 24 h. Fasting increased plasma corticosterone at 168 h. We also observed decreased bacterial killing ability and increased intestine melatonin 48 h after feeding. Meanwhile, stomach melatonin increased 168 h after fasting. Overall, feeding modulating immune response and the systemic hormonal and intestinal profile, as well as, fasting modulated stomach and plasma hormonal profile. We conclude that, as in mammals, feeding and fasting are able of modulating immunoregulatory hormones and systemic immune response of Bullfrogs.