Abstract: Objective To investigate the expression and clinical significance of miRNA21mRNA in ovarian cancer. Methods Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect miRNA21mRNA and PDCD4 protein levels in 108 cases of ovarian cancer patients,67 cases of borderline lesion,75 cases of benign lesion,and 35 cases of normal tissues. Results The expression levels of miRNA21mRNA in ovarian cancer,borderline lesion and benign lesion were significantly 11.3 times,6.8 times and 2.6 times respectively higher than those in normal tissues (P<0.01).The expression levels of miRNA21mRNA in borderline lesion were significantly 6.8 times higher than those in normal tissues (P<0.01,P＜0.01 and P＜0.05).The expression levels of PDCD4 in ovarian cancer borderline lesion,benign lesion and normal tissues were gradually and significantly decreased (P<0.05). Conclusion Up-regulated and down-regulated expressions of miRNA21mRNA and PDCD4 protein in ovarian cancer tissue might contribute to ovarian cancer carcinogenesis.