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Breast cancer is the most common cancer in women. Histologic grading is one of the prognostic factors in breast cancer. The present study performed in analytic descriptive method and based on the slide review of beast biopsies received in the pathology department of 5th Azar Hospital from 1976 to 1978, and on the basis of Bloom-Richardson criteria (Mitoses, tubule formation and nuclear pleomorphism). The results are consist of: 1) Infiltrating duct carcinoma is the most common histopathologic form, and tubular carcinoma is the least common 2) The most common age is 36-45 years 3) There is meaningful relationship between mitoses and tubule formation and between pleomorphism and tubule formation. But there is no relation between nuclear pleomorphism and tubule formation in the tumor. Histologic grading of breast carcinoma should be reported by pathologist for clear determination of prognosis and also the best choice for management of the tumors.