The experience of the use of the TRC-Mammotest machine for stereotactic fine needle biopsy (SFNB) of the breast in Perth is presented. During the period 20 October 1988 to 10 January 1990, 404 SFNB were performed on 389 women with impalpable, mammographically detected lesions of the breast. Surgical biopsy was performed in 73 cases, of which 38 were malignant, giving a benign to malignant ratio in less than 1:1. The sensitivity for detecting cancer was 95%, with a positive predictive value of 100%. Using a combination of the mammographic and cytologic rating for the likelihood of cancer, all the cancers were detected and no cancers have developed in those considered mammographically and cytologically benign. The importance of a combined assessment of mammography and cytology in the management of patients with mammographically detected abnormalities is stressed.