Growth hormone (GH) regulates anabolic metabolism via activation of the STAT5b transcription factor and reduces mucosal inflammation in colitis. Peroxisome proliferator-activated receptor (PPAR) gamma suppresses mucosal inflammation and is regulated by GH through STAT5b. We hypothesized that the GH:STAT5b axis influences susceptibility to colitis via regulation of local PPARgamma abundance. Colon biopsies from children with newly diagnosed Crohn's disease (CD) and controls were exposed to GH in short-term organ culture. Trinitrobenzene sulfonic acid (TNBS) administration was used to induce colitis in STAT5b-deficient mice and wild-type controls, with and without rosiglitazone pretreatment. GH receptor, STAT5b, PPARgamma, and nuclear factor kappaB activation and expression were determined. Epithelial cell GH receptor expression and GH-dependent STAT5b activation and PPARgamma expression were reduced in CD colon. STAT5b-deficient mice exhibited reduced basal PPARgamma nuclear abundance and developed more severe proximal colitis after TNBS administration. This was associated with a significant increase in mucosal nuclear factor kappaB activation at baseline and after TNBS administration. Rosiglitazone ameliorated colitis in wild-type mice but not STAT5b-deficient mice. GH-dependent STAT5b activation is impaired in affected CD colon and contributes to chronic mucosal inflammation via down-regulation of local PPARgamma expression. Therapeutic activation of the GH:STAT5b axis therefore represents a novel target for restoring both normal anabolic metabolism and mucosal tolerance in CD.