A series of 1956 fine-needle aspiration biopsies (FNAB) of breast masses is described. The diagnostic accuracy of this series (sensitivity, 95.7%; specificity, 89.6%; predictive value of positivity, 95.9%; and efficiency, 94.0%) was compared with that published in the literature. Statistically significant differences were found between the level of diagnostic accuracy in series published by pathologists who diagnosed smears prepared by clinicians and surgeons (Group A), and those published by pathologists who performed palpation and aspiration, and made the cytologic diagnosis by themselves (Group B). These differences mainly consisted of a lower number of false-positives and "unsatisfactory" samples in Group B series.