Neuroendocrine carcinomas of the uterine cervix are rare tumors with early metastases, highly aggressive clinical behavior, and poor clinical outcome. Several adhesion molecules like cadherins have been tested in an attempt to explain their unique characteristics. Cluster differentiation 44 (CD44) is a widely expressed cell surface glycoprotein that serves as an adhesion molecule in cell-to-substrate and cell-to-cell interaction. We have examined the expression of the standard CD44 (CD44s) by immunohistochemical stains in the paraffin-embedded cervical neoplasm tissue of 17 cases of primary cervical neuroendocrine carcinoma, 28 cases of cervical adenocarcinoma, and 50 cases of cervical squamous cell carcinoma. Loss of CD44s expression was found in 16 of 17 neuroendocrine carcinomas, 14 of 28 adenocarcinomas, and three of 50 squamous cell carcinomas. The differences were statistically significant. We also examined immunohistochemically the expression of the BRG-1 subunit of the SWI-SNF complex, which has been reported to regulate the expression of CD44 in all cases. Loss of BRG-1 expression was observed in 12/16, 6/14, and 1/3 CD44s-negative neuroendocrine carcinomas, adenocarcinomas, and squamous cell carcinomas, respectively. This study suggests that loss of the CD44s molecule may imply special biological behaviors of cervical neuroendocrine carcinomas, and loss of expression of BRG-1 may contribute to this.