Because the histopathological features of some primary adenocarcinomas of the sinonasal tract may show considerable overlap, we assessed the diagnostic value of a panel of immunohistochemical markers in the distinction between these malignancies. Paraffin-embedded tumour tissue sections from a series of 39 primary adenocarcinomas of the sinonasal tract, including 25 cases of intestinal-type adenocarcinoma (ITAC), 10 cases of salivary gland-type carcinoma and 4 cases of tubulopapillary low-grade adenocarcinoma were immunostained for CDX-2, cytokeratin 7 and cytokeratin 20. Diffuse nuclear staining for CDX-2 was identified in 80% of ITACs, while all non-ITACs were negative. Staining for cytokeratin 20 was positive in 84% of ITACs, including all cases negative for CDX-2, but negative in all other adenocarcinomas. Cytokeratin 7 was consistently positive in 88% of ITACs and in 100% of non-ITACs. Normal sinonasal epithelia expressed cytokeratin 7, but not CDX-2 and cytokeratin 20. Staining for CDX-2 and cytokeratin 20 has potential use in separating ITACs from other primary malignant glandular neoplasms of the nasal cavities and paranasal sinuses.