Free-feeding adult male Lewis rats were administered intraperitoneal (i.p.) Delta(9)-tetrahydrocannabinol (THC) in doses of 0.5, 1.0 and 2.5 mg/kg, and effects on food intake were measured at 1, 2, 4, 6 and 24 h postinjection. Rats were fed rat chow, a high-fat diet (HF) or a high-fat sweetened (HFS) diet. Small increases in HF and HFS intake following doses of 0.5 or 1.0 mg/kg were seen at 1, 2 and 4 h, but not 6 or 24 h compared to vehicle intake. Increases following 0.5 and 1.0 mg/kg did not differ from each other at any time point and 2.5 mg/kg produced smaller differences at all time points. There was no difference between HF or HFS intake at any time point although larger increases were seen in the HF group compared to both chow and HFS following 0.5 and 1.0 mg/kg. This work confirms previous data in both humans and rats indicating a stimulatory role for cannabinoids in ingestive behavior.