Fine-needle aspiration (FNA) biopsy is increasingly used in the diagnosis and biological characterization of breast carcinomas in patients who receive preoperative chemotherapy. In this context, nuclear cytologic grade supplemented by DNA content could play an important role in the morphologic assessment of breast cancer. In this study, DNA ploidy pattern, analyzed by flow cytometry on FNAs from 92 primary breast carcinomas, was related to cytologic nuclear grade. Twenty-seven samples were cytologic grade 1, 33 were grade 2, and 32 were grade 3. Ploidy correlated with cytologic nuclear grade (P = 0.0001). Thirty percent of grade 1, 55% of grade 2, and 84% of grade 3 tumors were DNA aneuploid. For 30 of the 92 FNAs, it was possible to compare nuclear cytologic grade with the corresponding histologic grade using the Scarff, Bloom, and Richardson system. A high concordance (80%) between nuclear grade on FNAs and histologic grade was found. DNA flow cytometry in combination with nuclear cytologic grade might represent additional information for the characterization of breast cancer diagnosed by FNA.