Abstract: Objective 　To study the expression of midkine in gast ric cancer and the relationship with biolog2 ical behaviors. Methods 　Immunohistochemical SP technique was used to detect the expression of MK in 88 cases of gast ric cancer and paratumor tissues around gast ric cancers. Results 　The expression of MKin cancer specimens was significantly higher than that in the relevant panatumor tissues. The correlation was observed between the expression of MK and degree of cellular differentation, invasive extent and clinical stage. Whereas, there was no significant relation observed with gross size and metastasis node. Conclusion 　MK protein may play a role in tumorgenesis and/ or progression in gast ric cancer. Moreover, MK pro2 tein seems to reflect the progression stage of gast ric cancer.