Rats were pretreated with systemic infusions of vehicle or exendin-4 prior to fentanyl self-administration test sessions. Food intake, water consumption, and body weight were measured up to 24 hours post infusion. In self-administration tests, total active lever responses (A) and total fentanyl infusions (B) were significantly decreased in rats pretreated with 0.72 nmol/kg exendin-4 versus vehicle (n=27/treatment; *p<0.05, Bonferroni). (C) 24-hour kaolin intake was significantly increased in rats pretreated with 0.72 nmol/kg exendin-4 compared to vehicle (n=16/treatment; *p<0.05, Bonferroni). (D) Exendin-4 significantly decreased cumulative chow intake in fentanyl-experienced rats compared to controls (n=16/treatment; *p<0.05, Bonferroni). (E) No effects of systemic exendin-4 were found on 24-hour water intake in fentanyl-experienced rats. (F) Exendin-4 significantly decreased body weight in fentanyl-experienced rats compared to controls (n=16/treatment; *p<0.05, Bonferroni).