Occasional rare benign and malignant breast tumours present diagnostical difficulties, how a report on 8 rare forms of tumours among 564 breast rumors (351 benign, 213 malignant) of the years 1965--1972 at the Universitäts-Frauenklinik Greifswald shows. We found among 351 benign breast tumours 2 rare forms: 1 tubular adenoma and 1 nodular lymphoreticulosis. We diagnosed among 213 malignant breast tumours 6 rare tumour-types: one at a case an unilateral respectively a bilateral noninvasive lobular carcinoma from the carcinoma-in-situ-type, 1 spindlecell- and 2 reticulosarcoma, which in one case the starting-point of the heterogeneous differentiated reticulosarcoma was obvious situated in a teratoid tumour. Last case dealt with a real cystosarcoma phylloides, of which oncological and terminological problems were additional discussed.