Signal transducer and activator of transcription 3 (STAT3) has been regarded as an oncogene in many types of cancers. However, its role in cervical carcinogenesis is not well determined. The purpose of this study was to evaluate the expression patterns of STAT3 in cervical intraepithelial neoplasia (CIN), normal cervix (NC), and squamous cell carcinoma (SCC) to explore its possible role in cervical carcinogenesis. Paraffin-embedded sections from 83 patients including 20 CIN 1, 10 CIN 2, 26 CIN 3, and 27 comparative cases of 10 NC and 17 stage Ib SCC were collected in this study. Immunohistochemistry was performed to analyze the expression patterns of STAT3, and the results obtained were categorized by a semiquantitative method and were further correlated with the CIN histopathologic grade and the proliferation marker, Ki-67, using the chi2 test. Our results showed that nuclear STAT3 expression was predominantly in the squamous epithelial cells, and that high-grade CIN and stage Ib SCC lesions had a higher nuclear STAT3 expression when compared with NC and CIN 1. Furthermore, the nuclear STAT3 expression in CIN was significantly correlated with Ki-67 expression (p = 0.025), but not CIN lesion grade. In summary, our results indicate that an altered STAT3 expression in CIN is correlated with cell proliferation but may not have a direct contribution to cervical carcinogenesis.