The Cytology and Core Needle Biopsy Subcommittee, organized under the Rules Committee of the Japanese Breast Cancer Society, has prepared a new form for breast cytology reports. This reporting form consists of "diagnostic categories" and "recommendations." The "diagnostic category" is either "specimen inadequacy" or "specimen adequacy." The judgment on "specimen adequacy" is subdivided into four categories: "normal or benign," "indeterminate," "suspicious for malignancy," and "malignant." The "recommendation" indicates descriptions of cytological features and estimated histological type of tumor (these descriptions should be as detailed as possible). On the basis of an analysis of cytological data from 3,439 cases performed before preparing this form, the subcommittee has attached the following recommended goals to this form: (1) the percentage of "specimen inadequacy" should be 10% or less of all samples, (2) the percentage of "indeterminate" samples should be 10% or less of all "specimen adequacy" cases, and (3) 90% or more of "suspicious for malignancy" cases should be diagnosed as "malignant" in a subsequent histological examination. We hope that modification of this form, if it requires revision in the future, will be evidence-based, as was the process for compiling this set of rules.