Abstract: Objective To study the expression of p53、p21WAF-1 and p63 in gastrointestinal stromal tumors(GIST)and the relationship with clinicpathological factors.Methods The expression level of p53、p21WAF-1 and p63 in 70 cases of GIST was examined by using SP immunohistochemical method.Results The positive expression rate of p53、p21WAF-1 and p63 was 62.86%、34.29% and 14.29% respectively.The positive expression of p53 was related to primary location of tumor, necrosis, tumor diameter, nuclear mitosis and Fletcher grading(P＜0.05).The positive expression of p21WAF-1 was related to tumor cell types, tumor diameter, nuclear mitosis and Fletcher grading(P＜0.05).The positive expression of p63 was related to necrosis and nuclear mitosis(P＜0.05).The expression of p21WAF-1 showed negative correlation with that of p53.Conclusion The expression level of p53、p21WAF-1 and p63 was closely related with the biological behavior of GIST and might be considered as potential marker for the biological behavior of GIST.