microRNAs (miRNAs) play pivotal roles in controlling cell proliferation and differentiation. miRNA expression in human is becoming recognized as a new molecular mechanism of carcinogenesis. microRNA-34a (miR-34a), a member of the p53 network, was found to be regulated in multiple types of tumor. The purpose of this study was to define roles of miR-34a expression in cervical intraepithelial neoplasia with human papillomavirus infection, and its relationship with p53 protein expression. This study was performed to analyze expression of miR-34a by using qRT-PCR, and to evaluate p53 protein expression by using immunohistochemistry in 40 cases. Down-regulation of miR-34a expression was detected in 27 (67.5%) out of 40 cases and Immunoreactivity for p53 was found in 17 (42.5%) out of 40 cases. Nineteen (82.6%) of the 23 cases with a negative p53 expression showed a down-regulation miR-34a expression, there was a significant associations between miR-34a and p53 protein expression (P=0.04). These results suggest that miRNA-34a expression tend to be reduced depending on the advanced histologic grade, and down-regulation of miR-34a expression might be associated with inactivation of p53 protein expression by human papillomavirus infection.