Sonography has become a helpful adjunct to mammography mainly for a differential diagnosis between simple cysts and solid masses. The authors examined by ultrasound 134 palpable masses in the breast which had been previously evaluated by clinical examination and mammography and then submitted to biopsy or fine needle aspiration. The exact diagnosis of a simple cyst was made in 94.1% of the cases, whereas the diagnosis of fibroadenoma was made in 80% of the cases. Ultrasound examination proved to be useful in patients with dense breasts: in this group, 82.1% of the patients with a histologic diagnosis of benign status had a correct ultrasound diagnosis. In agreement with other authors, we believe that breast sonography has no part in screening programs.