The patient was a 30-year-old-pregnant woman (para 1, gradiva 1) without in utero exposure to diethylstilbestrol. A papillary and flat lesion was found by colposcopy in the uterine cervix in the routine examination at 10 pregnancy weeks. Biopsies showed papillary and tubular proliferation of malignant cells with clear glycogen-rich cytoplasm and malignant hobnail cells and were diagnosed as clear cell adenocarcinoma. The patient was treated by radical hysterectomy. The lesion of the cervix (10 × 15 × 5 mm) was clear cell adenocarcinoma with mild invasion into shallow myometrium (pTIb). An immunohistochemical study showed that the tumor cells were positive for pancytokeratins (AE1/3, CAM5.2, KL-1, and polyclonal wide), cytokeratin (CK) 7, CK8, CK18, CK19, epithelial membrane antigen, CA 125, p53 protein, and Ki-67 antigen (labeling = 95%). The tumor cells were negative for high-molecular weight CK (34βE12), CK5/6, CK14, CK20, vimentin, AFP, CEA, desmin, S100 protein, α-smooth muscle antigen, CD34, estrogen receptor, progesterone receptor, chromogranin, synaptophysin, neuron-specific enolase, and CD56. The patient is now of free of tumor. In the English literature, the present case is the second case of cervical clear cell adenocarcinoma during pregnancy, and the first case of cervical clear cell carcinoma investigating a wide range of immunoreactive antigens.