Traditionally, sonographically guided percutaneous needle biopsy has been used for the biopsy of large, superficial, and cystic masses. Today, however, many think that small, solid masses also can be biopsied accurately. Real-time sonographically guided biopsies of 126 consecutive solid masses that were less than or equal to 3.0-cm in diameter (less than or equal to 1.0 cm, 24; 1.1-2.0 cm, 42; 2.1-3.0 cm, 60) were performed to diagnose primary or secondary neoplasm. These masses were located in a variety of anatomic regions (abdomen, 92; neck, 31; breast, two; extremity, one). Clear visualization of the biopsy needle was accomplished by continuous real-time monitoring of the needle's position, primarily by using linear, phased-array transducers, large-caliber needles (18- to 19-gauge, when possible), and an echogenic screw stylet inserted coaxially within the biopsy needle. The correct cytologic/histologic diagnosis was established in 91% of the masses (less than or equal to 1.0 cm, 79%; 1.1-2.0 cm, 88%; 2.1-3.0 cm, 98%). No complications other than mild, localized discomfort were encountered. Our experience suggests that sonographically guided biopsy is a highly accurate and safe procedure that can be used to establish the diagnosis in solid masses that are 3.0 cm or less in diameter if proper techniques are used to clearly visualize the biopsy needle.