The results of aspiration biopsy cytology were clinically evaluated on the basis of clinical experience with 608 patients with breast cancer at the First Department of Surgery, Nagasaki University School of Medicine. Aspiration biopsy is of clinical value in making a diagnosis of small-sized tumors. There was no detrimental outcome to promote tumor-cell spread locally as well as to give rise to distant metastasis into the other organ. One should be aware of a no cell finding in relation to scirrhous carcinoma and intraductal papillomatosis. Emphasis is placed on recommendation of open biopsy without repeated aspiration maneuver
