Abstract: Objective To investigate the expression of hepatocyte growth factor activator inhibitor (HAI) - 1 gene in the tissues of prostatic carcinoma and its correlation with tumor angiogenesis.Methods The expression of HAI-1 gene was detected in 48 cases of prostatic carcinoma and 20 cases of prostatic hyperplasia tissues by semi-quantitative RT-PCR,and the expression of CD34 in the tissues mentioned above was detected by immunohistochemistry SP method.Thereafter,the microvessel density (MVD) was calculated in order to analyze the correlation of HAI-1 gene expression and the clinical pathological indicators of prostatic carcinoma.Results Thc positive expression rate of HAI- 1 gene was 85.00% in 20 cases of prostatic hyperplasia tissues and 52.08% in 48 cases of prostatic csarcinoma tissues (P<0.05).The positive expression rate of HAI-1 gene in A + B stage of prostatic carcinoma (71.43%) was significantly higher than that in C +D stage (37.04%) (P<0.05).The positive expression rate of HAI-1 gene in poorly differentiated group was obviously lower than that in moderately and highly differentiated groups (P<0.05).The MVD in prostatic carcinoma tissues was significantly higher than that in prostatic hyperplasia tissues (P<0.01).The expression of HAI- 1 gene was negatively correlated with MVD in prostatic carcinoma tissues (r=-0.647,P< 0.05).Conclusion The deficiency of HAI-1 expression may have a certain correlation with the development and infiltration metastasis of prostatic carcinoma.