Juvenile papillomatosis (JP) is a benign proliferative breast tumor rarely found in women older than 30 years of age that may exhibit considerable histologic atypia. Often these findings would be regarded as precancerous in older patients. Rarely, carcinoma and JP have been coexistent at diagnosis, but little is known about the risk for development of carcinoma after excisional biopsy of JP. To examine this issue, the authors reviewed a series of 41 patients with JP who had biopsies between 1960 and 1978 with a median follow-up of 14 years. Age at diagnosis ranged from 15 to 35 years (median, 19 years), whereas at last follow-up the patients were 22-48 years old (median, 36 years). Overall, 21 (58%) reported a positive family history for breast carcinoma, with mothers and maternal aunts being at highest risk. Six had bilateral JP. Subsequent breast carcinoma was diagnosed in four (10%) of the patients with JP. All of these patients were unusual because they had recurrent and bilateral JP. In two instances the changes were multifocal. Each had a positive family history for breast carcinoma. In this series, none of the patients with nonrecurrent unilateral, unicentric JP has thus far had subsequent mammary carcinoma develop. When counseling the JP patient one should take care not to exaggerate her near term risk for development of carcinoma. The present data suggest that concern should be greatest for women with a positive family history and recurrent bilateral JP.