Abstract: Objective To evaluate the expression of KLK7 mRNA（KLK7） in prostate tissues of different pathology including normal prostate,BPH and prostate cancer,in order to discuss the relationship of this gene with the benign and malignant prostate diseases,and to demonstrate the relationship of its expression level with the occurrence and development of the tumor. Methods Quantitative real-time PCR was used to quantify the KLK7 expression in 15 cases from normal prostate tissues,25 cases of BPH as well as 53 cases of prostate cancer.We compared its different expression between benign and malignant prostate tissues;different clinical tumor stage;with or without bony metastasis. Results We found a significant decrease in KLK7 expression in prostate cancer compared with their normal or benign counterparts (P＜0.05),this difference was also observed in late stage prostate cancer compared to local ones,and there was statistical significance(P＜0.05);its expression level had no significant difference between tissues with or without bony metastasis(P＞0.05). Conclusion KLK7 expresses lower in prostate cancer tissues and in later stage ones,it suggests this gene is hopeful to be the molecular marker for diagnosis and prognosis estimation of prostate cancer.