Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent intestinotropic hormone that promotes intestinal growth via increased intestinal proliferation and decreased apoptosis, as well as increasing nutrient absorption and barrier function. The long-acting analog h(Gly²)GLP-2[1–33] is currently being tested for treatment of short bowel syndrome and Crohn's disease. However, the role of GLP-2 in colon carcinogenesis is controversial. To assess the intestinotropic effects of exogenous and endogenous GLP-2, C57Bl6/J mice were injected with 1µg h(Gly²)GLP-2[1–33], 30 or 60ng hGLP-2[3–33], a GLP-2 receptor antagonist, or PBS (4wk, bid, s.c.). Chronic h(Gly²)GLP-2[1–33] increased small intestinal weight/body weight (p<0.001), villus height (p<0.001), crypt depth (p<0.001) and crypt cell proliferation, as measured by expression of the proliferative marker Ki67 (p<0.05–0.01). In contrast, chronic hGLP-2[3–33] decreased (p<0.05) small intestinal weight/body weight and colon weight/body weight (p<0.05). To assess the carcinogenic effects of endogenous and exogenous GLP-2, separate mice were injected with azoxymethane (AOM, 10 mg/kg, 4wk, q7d, i.p.), followed by 1.5µg h(Gly²)GLP-2[1–33], 30ng hGLP-2[3–33], or PBS (4wk, bid, s.c.) 2 or 12 weeks thereafter. At 10 or 46 wk after AOM treatment, the numbers of aberrant crypt foci increased with h(Gly²)GLP-2[1–33] (p<0.001) and decreased with hGLP-2[3–33] treatment (p<0.01–0.05). Furthermore, mucin-depleted aberrant foci, consistent with progressive dysplasia, were almost exclusively present in h(Gly²)GLP-2[1–33]-treated mice (p<0.01–0.001). Additionally, adenocarcinomas developed in h(Gly²)GLP-2[1–33]-treated mice, but not in those receiving hGLP-2[3–33] or PBS. Taken together, these studies indicate that chronic treatment with GLP-2 enhances colon carcinogenesis, while antagonism of the GLP-2 receptor decreases dysplasia, with possible implications for human therapy.