Adenocarcinoma admixed with neuroendocrine carcinoma of the uterine cervix is a rare malignancy with a poor prognosis, and few reports have described the cytological features of this carcinoma. To characterize the cytological features of this malignancy in cervical smears, we report a case of a 52-year-old Japanese woman with cervical adenocarcinoma admixed with small cell neuroendocrine carcinoma (SCNEC). Cytologically, there were two types of cells with different sizes. The smaller cells formed clusters, which showed a partially Indian file pattern, a high nuclear/cytoplasmic ratio, and hyperchromatic nuclei. In contrast, the larger cells showed cytological features of adenocarcinoma, indicating a glandular-like pattern. Histological examination of biopsy specimens revealed that the tumors were composed of almost equal areas of SCNEC and adenocarcinoma. Neuroendocrine differentiation was confirmed by immunohistochemistry for synaptophysin and CD56. Thus, when adenocarcinoma cells are detected in smears, attempts to search for SCNEC cells should be made by combined cytological and histological analyses in order to reach an accurate diagnosis of the carcinoma in the uterine cervix.