The role of the pathologist in breast cancer is discussed from the practical viewpoint. For primary diagnosis surgical biopsy is preferred. Of prognostic significance are the size of the tumor and the number of regional lymph nodes affected. The different histological patterns have little prognostic bearing, with the exception of some rare special types such as medullary or mucinous carcinomas. Histological and/or cytological "grading" is too time-consuming for practical purposes. The pathologist is confronted with new problems by non-palpable "minimal breast cancer" detected by mass screening methods. The solution to these problems requires close interdisiplinary cooperation. In In the broad field of cystic diseases of the breast there is a need for a better histological definition of what constitutes a true premalignant lesion. Finally, the problems of multicentric and bilateral breast cancers are mentioned.