A sample of 1744 self-selected, mostly asymptomatic women was used to evaluate exfoliative cytology of nipple secretions as a screening technique for breast atypias. Results indicated: 1) overall frequency of breast fluid recovery was 49%, and related to age, phase of reproductive life, parity, history of lactation and birth control pill use at the time of sampling. 2) Frequency of satisfactory smears was 36% of breast fluid specimens, and related to subject's phase of reproductive life. 3) 2.8% of all satisfactory smears exhibited atypical cells. Biopsy of 4 subjects with atypical smears indicated 3 with nonmalignant epithelial atypias and 1 with early ductal carcinoma. Follow-up of women who did not have atypical smears indicated 12/1092 (1.1%) with nonmalignant epithelial atypias and none with carcinoma. 4) The number of cases of malignant (1) and nonmalignant (7) breast disease detected was close to the expected number in the population sampled (1.98 and 7.25, respectively).