Eighteen mammographically detected, nonpalpable breast lesions, comprising 14 parenchymal and four ductal lesions, were studied. Kopan's localization needle was used, guided by an alpha-numerical plate in the parenchymal lesion and ductography with methylene blue dye for the ductal lesions. Three (two stellate lesions, one microcalcification) out of 14 (21%) were positive for invasive cancer. The rest showed ductal epithelial hyperplasia and fibrocytosis disease. All the ductal lesions were correctly localized and confirmed pathologically as papillomata. The three positive cases for carcinoma were under 50 years of age and two were under 40 years of age. Cognizance will have to be taken of the age group involved in determining the lower limit for breast cancer screening when implemented. Localization of intraductal lesions with methylene blue dye facilities surgical identification.