To evaluate the role of cyclooxygenase (COX)-2 during cervical carcinogenesis, we investigated COX-2 expression in the dysplastic epithelium and stromal cells of cervical intraepithelial neoplasia (CIN). Immunohistochemical analysis with COX-2 antibody was performed on 148 paraffin-embedded tissue specimens of patients who were diagnosed as CIN in our institute. COX-2 expression was evaluated separately in the dysplastic epithelium and stromal cells of CIN. The relationships between COX-2 expression and clinicopathologic variables were examined. For the dysplastic epithelium, COX-2 expression was negative in 137 (92.6%) and positive in 11 (7.4%) specimens. For the stromal cells, COX-2 expression was negative in all specimens. The COX-2 expression in dysplastic epithelium was higher in older (P= 0.038) or postmenopausal (P= 0.025) women. In conclusion, COX-2 expression was observed only in the dysplastic epithelium but not in the stromal cells of CIN. The COX-2 expression in dysplastic epithelium was associated with age and menopausal status.