BACKGROUND Sex chromatin is a plano-convex to triangular DNA mass measuring approximately 1μm in size and lying adjacent to the inner side of nuclear membrane in the somatic cells of the females. There is consistent loss in the sex chromatin percentage in the carcinoma cases in comparison to benign lesions and normal individuals. OBJECTIVE To know the correlation between the sex chromatin status in female breast tumors on paraffin sections, buccal smears and peripheral blood films. METHODS The study was conducted on the paraffin sections prepared from carcinoma breast patients from their lumpectomy and mastectomy specimens. Buccal smears and a peripheral blood films were also prepared from each patient. CONCLUSIONS The control group had shown a mean sex chromatin of 54.6±6.73% which was found to be similar to the mean sex chromatin percentage in the fibroadenoma breast cases i.e. 54.91±6.06%. However, the mean sex chromatin in the carcinoma breast cases was markedly reduced i.e. 8.22±6.03%. Maximum no. of fibroadenoma cases (67%) were in the younger age group i.e. 15 to 25 year, while maximum number of carcinoma breast cases (42%) occurred in the 4(th) and 5(th) decade. CONCLUSIONS There is a loss of sex chromatin in cases of carcinoma breast and is associated with poor histological markers. A statistically significant correlation was also found between sex chromatin status and microscopic grading in carcinoma breast. The tumors with higher microscopic grade had lower sex chromatin as compared to those with lower microscopic grading.