Microdochectomy is the standard treatment of galactographically suspicious breast lesions. Precise preoperative marking of the suspicious duct and intraductal lesions facilitates selective minimal-volume microdochectomy. Methylene blue dye staining fulfills this criterion. A retrospective review of our experience of preoperative methylene blue staining in 30 patients with unilateral spontaneous nonlactiferous single duct nipple discharge operated on during 1986-1995 in the Oulu University Hospital for galactographically suspicious breast lesions. Galactography was successful in 29 out of 30 (93.3%) cases. Preoperative methylene blue staining was attempted in all cases on the day of surgery and it was successful in 22 (73.3%) cases making subsequent selective minimal-volume microdochectomy easy to perform. The failure of methylene blue staining led to quadrantectomy in 4 cases and smaller breast resections in the remaining 4 cases. Preoperative methylene blue dye staining crucially facilitates selective minimal-volume microdochectomy. An interval between primary galactography and later methylene blue staining leads to failures in approximately one quarter of the cases. A higher success rate would necessitate scheduling the microdochectomy on the same day as the primary galactography (and the subsequent methylene blue staining in suspicious cases).