Immunohistochemical expression of p53 protein was studied in FNA specimens of 20 breast ductal carcinomas, 20 fibroadenomas and 20 atypical ductal hyperplasia of the breast. Nine cases of breast carcinomas (45%), five fibroadenomas (25%) and four atypical ductal hyperplasia (20%) were found to be p53-immuno-positive. A statistically significant difference was found among p53 staining index of breast carcinomas (mean 72.55%), fibroadenomas (mean 41.2%) and atypical ductal hyperplasia (mean 34%). Variations in p53 expression among individual breast carcinomas was found, and these variations may correlate with prognosis.