Debate over which biopsy needle is the best has intensified recently with the introduction of automated biopsy guns including the 18-gauge long-throw and short-throw Biopty, the 18-gauge Cook, and the 14- and 18-gauge Klear Kut. To evaluate the efficacy of these mechanized biopsy guns versus that of conventional manual biopsy needles in the acquisition of adequate tissue for histopathologic evaluation, open hepatic and renal biopsies were performed in 15 pygmy pigs. The specimens were evaluated separately in a double-blind fashion by two histopathologists using graded criteria. Overall, the best results were obtained with the manual 14-gauge Tru-Cut needle, the long-throw 18-gauge Biopty gun, and the 18-gauge Cook biopsy gun. By comparison, the aspiration-type needles did not perform as well when considered as a group. Seven other needles scored well in the biopsy of either the liver or kidney, but not in both. Disappointing results were obtained with the Klear-Kut guns (both 14- and 18-gauge) an the Vacu Cut and PercuCut needles.