Abstract: Objective 　To investigate the effect s of inhibiting factor of cell cycle regulation2 p57kip2 protein and gene in the genesis and progression of human colorectal adenocarcinoma. Methods 　The expressions of p57kip2 protein in tumor tissues of 37 patient s with colorectal adenocarcinoma and in normal colorectal mucosal tissues of 26 subject s were detected by SP immunohistochemical technique. The expressions of p57kip2 gene mRNA in tumor tissues and adjacent colorectal tissues of 32 patient s were detected by RT2 PCR. Results 　p57kip2 protein positive2expression rate in tumor tissues of colorectal adenocarcinoma was 40. 5 %, which was lower than that in normal colorectal mucosal tissues (χ2 = 5. 039, P < 0. 05), p57kip2 protein positive2expression correlated significantly with tumor cell differentiation and lymph node metas2 tasis (χ2 = 8. 914, χ2 = 4. 416, P < 0. 05) ; p57kip2 gene mRNA positive2expression rate in tumors of color2 ectal adenocarcinoma was 34. 4 %, which was lower than that in adjacent colorectal mucosal tissues (χ2 =4. 016, P < 0. 05), and was not correlate remarkably with tumor cell differentiation, lymphy node metas2 tasis ; the expression level of p57kip2 gene mRNA in tumor tissue was lower than in adjacent corlorectal mucosal tissues ( P < 0. 05) . Conclusion 　The decreased expression of p57kip2 protein may play an impor2 tant role in the genesis and progression of colorectal adenocarcinoma. The decreased expression of p57kip2 gene mRNA may cont ribute to the occurrence of colorectal adenocarcinoma. The decreased expression of p57kip2 protein may relate with the decreased expression of the expressions of p57kip2 gene mRNA.