The bioptic strategy in breast cancer rests on the following basic conditions at the Department of Surgery K, Odense University Hospital: Firstly, clinical mammography precedes any bioptic procedure. Secondly, the bioptic procedure must secure representative tissue for histological examination. Thirdly, knife-biopsy should preferably be excisional. Finally, tissue examination is exclusively done by the pathologist and always on unfixed tissue. The application and outcome of the employed biopsy methods are illustrated by a series of 365 women with operable, primary invasive breast cancer, treated from 1982 to 1987. Definitive surgery was mainly based on excisional (62%) or needle biopsy (24%). Three-fourths of the patients were treated by the one-stage procedure. However, within the last year of the period the rate of needle biopsy and two-stage procedures was doubled, increasingly employing core-aspirating needle biopsy synchronously with mammography and done by the radiologist. So far, patient compliance and histological outcome is satisfactory.