Fine needle aspiration cytology is considered as a useful diagnostic procedure in management of patients with breast lesions. This study was undertaken to evaluate the scoring system of Masood in the interpretation of breast aspirates, to establish the most useful cytologic criteria for the diagnosis of breast lesions, and to subclassify the benign breast diseases. To assess the feasibility of a cytologic grading system, 57 cases of benign breast disease, 61 cases of malignant breast disease were studied, respectively. The aspirates were evaluated for the cellular arrangement, the degree of cellular pleomorphism and anisonucleosis, and the presence of myoepithelial cells and nuceoli. Values ranging from 1 to 4 were assigned to each criterion and the sum of the individual values was made for each case. The presence of stroma, apocrine metaplasia, foamy histiocytes and inflammatory cells, background of the smear, and cellularity were also evaluated. Cut-off value of the scoring system of Masood between benign and malignant lesion was 15. Among the cytologic criteria, cellular arrangement, presence of myoepithelial cells, nucleoli, and stroma, status of chromatin pattern, and background of smear were useful criteria in the differentiation between benign and malignant lesions. Application of the scoring system of Masood does not always make the accurate diagnosis and the subclassification of benign breast disease.