Abstract: Objective : To study the effect of the mutant p27 gene (p27mt gene) on growth of the colorectal cancer cell line SW480 and to evaluate the therapy significance by DNA ploidy analysis and apoptosis measuration. Methods : Adenovirus vector with exogenous mutant p27 gene was transfected into the colorectal cancer cell line SW480, the transfer efficiency and expression effect of p27mt gene were examined by X-gal stains and western blot analysis,the growth of SW480 in vitro was determined by cell counting. Flow cytometric analysis was used for observing cell cycle. The Apoptosis was measured by D A N fragment analysis. Results : Transfer efficiency reached 100% in SW480 when adenovirus infection ability was over 50MOI, the efficiency expression of p27mt gene was measured using western blot. A 77.90% of cells was arrested in G₀ /G₁ in experimental group, while Ad-LacZ group and blank contrast group were 27.57% and 25.29% in G₀ /G₁, respectively. The curve of growth showed that p27mt gene had a inhibition effect on SW480. DNA fragment analysis demonstrated that p27mt could induce SW480 cell apoptosis. Conclusion : Adenovirus gene transfer of p27mt induces the growth suppression and the cell cycle arrest in G₁-S and apoptosis of colorectal cancer cell line SW480. The mechanism of growth suppression may be related to apoptosis and cell cycle arrest.