To study the relationship between the expression and contents of cell adhesion molecule CD15 and differentiation and lymph nodes metastasis of breast carcinomas, CD15 expression and its contents in 94 cases of breast carcinomas and or cases of normal breast tissue were evaluated by microwave-SP immunohistochemical chenique combined with image analysis. CD15 immunoreactivity in normal breast tissue was mainly localised at the border of gland, but in breast cancer tissues it was mainly localised in the membrane and cytoplasm. Positive rate of CD15 and its average optic density in breast carcinomas were significantly higher than those in normal breast tissue (Ｐ＜0.05 and Ｐ＜0.001, respectively). The worse tumors differentiated and the earlier lymph nodes metastasized, the higher CD15 expressed and its optic density was measured (Ｐ＜0.05 and Ｐ＜0.001, respectively). These results suggest that CD15 expression and its contents might be a useful indicator to evaluate the malignancy and biological features, and could be considered as a good prognostic predictor for breast carcinomas.