In a series of 9,312 women who consulted one of the authors with a complaint of disease of the breast between 1959 and 1991, nipple discharge was the presenting symptom in 448 (4.8 percent). Nipple discharge was spontaneous in 243 (2.6 percent) and provoked in 205 (2.2 percent) of the patients. The ages of the patients ranged from 13 to 75 years (mean of 42.5 years) in the spontaneous and 16 to 70 years (mean of 37.8 years) in the provoked discharge group. When a palpable mass was found, biopsy was undertaken, while in instances of nipple discharge only, subareolar exploration was performed. Of the 115 patients in the spontaneous and 25 patients in the provoked groups who underwent biopsy, the most frequent cause of nipple discharge was intraductal papilloma (47.8 percent). Nipple discharge was the result of carcinoma in 35 patients (14.4 percent) in the spontaneous and six patients (2.9 percent) in the provoked group, respectively. In patients with a palpable mass, the incidence of carcinoma was 61.5 percent compared with 6.1 percent in patients with nipple discharge only. Patients presenting with nipple discharge should undergo biopsy or subareolar exploration based on the presence or absence of a palpable tumor. The patients in whom no clinical findings could be detected should have follow-up evaluation at regular intervals.