Abstract: Objective：To evaluate the correlation of Ki67 labeling index（LI），clinicopathological features and invasiveness of gastrointestinal stromal tumor（GIST）.Methods：This retrospective study was conducted in 155 patients with endoscopic and surgical radical resection of primary GIST.Patients were divided into groups base on Ki67 LI.The clinical and pathological data were analyzed to evaluate the significance of Ki67 LI in risk classification of GIST.Results：The statistically significant differences of Ki67 LI were observed in the following factors：tumor site，tumor size，mitotic index，risk grade，tumor with ulcer，hemorrhage，necrosis and metastasis（P<0.05）.And those factors and Ki67 LI were statistically well correlated（P<0.05）.There was no significant difference of Ki67 Li shown in the age，gender，CD117，DOG1 and CD34 positive rates（P>0.05）.The risk classification according to Ki67 LI was highly agreement with NIH classification，Kappa=0.394（P<0.05）.Conclusion：Ki67 LI is significantly associated with the progression and the invasive of GIST，it can be used as a supplement to the NIH classification and is an important indicator for GIST risk classification and predicting prognosis.

Key words: Ki-67, gastrointestinal stromal tumor, risk classification, clinicopathological features