A decision model was used to compare the relative costs of the 14-gauge automated gun technique to the 14-gauge and 11-gauge vacuum-assisted techniques for stereotactic biopsy of noncalcified breast lesions. Probability and cost variables were estimated from clinical experience with 76 automated gun biopsies, seventy-eight 14-gauge vacuum-assisted biopsies and thirty-nine 11-gauge vacuum-assisted biopsies. The 14-gauge automated gun was the preferred strategy from a cost standpoint: the 14-gauge vacuum technique was 1.19 times more expensive, and the 11-gauge was 1.22 times more expensive.