Abstract: Objective To investigate the role of Id2 in the development and growth of familial adenomatous polyposis in Apc^Δ716/+ mice. Methods Apc^Δ716/+ mice were hybridized with Id2 defi cient mice, and the tumor susceptibility in intestine was compared. The total intestine polyps number and overall load of Apc^Δ716/+Id2^+／+mice and Apc^Δ716/+Id2^-/- mice were analyzed and the changes in intestinal polyps were observed. The western blot and in situ hybridization were performed to investigate the expression of Id2 in intestinal polyps. Result The protein and mRNA expression of Id2 was increased in the intestinal polyps of Apc^Δ716/+ mice. Id2 defi cient in Apc^Δ716/+ mice resulted in signifi cant decrease of total polyps number and polyp numbers of with different size in the intestine at 8 weeks (P all ＜0.05). Conclusion Id2 expression is increased in the polyps.Id2 deficiency could inhibit intestinal adenomatous polyps of APC^Δ716/+ mice. Importantly, these studies also suggest that Id2 may act as a polyp promotor for human familial adenomatous polyposis.