In order to compare cytologic findings ol breast carcinoma in fine needle aspiration cytology (FANC) with histologic findings and prognostic factors including histologic grading, lymph node metastasis and stage, 79 cases of infiltrating ductal carcinoma diagnosed by FANC and confirmed by histology were analysed. We especially attempted to col relate nuclear grade, cellularity and smear pattern with histologic grade, type, status of lymph node metastasis and stage. The results are as fellows. 1. High nuclear grade was correlated with high histologic grade, lymph node metastasis and advanced stage. 2. Individual cell pattern was more frequently identified in high histologic grade and scirrhous or solid-tubular type than in low histolgic grade and papillotubular type. 3. Cellularity increased with higher histologic grade and lymph node metastsis. However cellularity was low in scirrhous type. 4. There is no relationship between nuclear grade and histologic type, between smear pattern and lymph node metastasis or stage, and between cellularity and stage. These results suggest that cytologic findings of breast carcinoma such as nuclear grade, cellularity and smear pattern are indicative of histologic findings in relation to histolgic grade and type. Especially, nuclear grade of FANC may yield valuable prognostic information.