The recognition of an adhesive role for the CEA-related antigens emphasizes the need for clear demonstration of the changes in CEA expression and subcellular localization between normal and neoplastic tissues. Using a panel of monoclonal and polyclonal antibodies, membranous and cytoplasmic CEA expression was seen in 50 invasive cervical squamous carcinomas in four distinct patterns dependent on tumour type and differentiation. Membranous CEA expression is a marker of differentiation in squamous carcinomas and may influence tumour behaviour and hence patient survival. Strong CEA positivity was seen on the endothelium of vessels containing tumour in ten cases where vascular metastases were prominent. Staining of these ten cases revealed concomitant sialated Lewis X positivity in tumour cells with weak endothelial positivity in three cases; cervical squamous tumour cells may localize to vascular endothelium, and hence disseminate, through specific binding of CEA and/or sialated Lewis X.