Local adenoviral vector encoding murine interleukin 10 (AdvmuIL-10) was therapeutic for established murine colitis. IL-10−/− mice (n=10/group) with clinical evidence of colitis and C57BL/6×DBA1 wild-type controls (n=5/group) received 5×108 PFU of AdvmuIL-10, empty cassette adenoviral vector (Adv0), or vehicle by rectal instillation under light sedation. (A) Clinical score (one point each for rectal mucous, rectal prolapse, diarrhoea, and weight loss >5% body weight) and (B) stool IL-1β levels were measured weekly, and are expressed as mean (SEM) for each group. **p<0.01, ***p<0.001, two way ANOVA.