<正>Metaplastic carcinoma of the breast encompasses a heterogeneous group of tumors with variable components of sarcomatoid, squamous or poorly differentiated carcinomas. We reviewed a series of 19 cytologic preparations of metaplastic carcinomas to assess diagnostic cytologic features. Seventeen cases of fine needle aspirates of histologically proven metaplastic carcinomas (4 monophasic spindle cell carcinoma, 4 squamous cell carcinoma and 11 biphasic tumors) were reviewed, with an emphasis on the presence of poorly differentiated carcinoma, squamous cell carcinoma, atypical spindle cells, benign stromal fragments and necrosis. All cases were diagnosed as malignant, with 68 % of cases showing moderate to high cellularity, and 47% showed necrosis. If the tumors were analyzed according to the constituting components histologically, 7, 15 and 8 cases respectively possess poorly differentiated carcinoma cells, sarcomatoid malignant cells and squamous carcinoma cells; whereas these components were identified in 11, 10 and 7 cases cytologically respectively. In only five of the 11 biphasic carcinomas were dual tumor populations identified in the cytologic preparations; and in the only case with chondroid stroma, the stromal material was cytologically identified. Our conclusion is that i dentification of metaplastic carcinoma in cytology remains problematic. There appears to be morphologic overlap between various components. The identification of dual components, unequivocal squamous carcinoma cells and chondroid stroma is helpful for diagnosis, but it is uncommon. The presence of poorly differentiated carcinoma cells with suggestion of focal spindle morphology is another clue to the suggestion of metaplastic carcinoma.