MUC-1 is synthesized as a single polypeptide that then undergoes proteolytic cleavage, and is associated with the epidermal growth factor receptor tyrosine kinases. In malignancies, MUC-1 may function as an anti-adhesion molecule, but can also promote adhesion and presumably metastasis.Expression of MUC-1, -2, -4 and -5AC was evaluated on tissue microarrays of gastric carcinomas (n = 237) and adjacent non-cancerous mucosa specimens (n = 89) by immunohistochemistry and compared with clinicopathological parameters and survival time of the patients.MUC-1 was found to be highly expressed in gastric carcinomas in comparison with noncancerous mucosa (p 0.05). Intestinal-type carcinomas showed more MUC-1 expression than their diffuse-type counterparts (p 0.05). Cox's analysis showed three independent prognostic factors, depth of invasion, lymphatic invasion and venous invasion, to affect the relationship between MUC-1 expression and prognosis.Up-regulation of MUC-1 expression may be involved in pathogenesis, invasion, metastasis and differentiation of gastric carcinoma. Altered expression might therefore be employed as an indicator of pathobiological behavior of gastric carcinoma. MUC-1 expression was found to be a prognostic factor for gastric carcinoma patients, albeit not independent of parameters of invasion.