This study evaluated the ability of laparoscopic ultrasonography to detect, localize, and characterize focal liver masses. Laparoscopic ultrasonography and CT portography of the liver were performed in 13 patients with known or suspected malignancy. Laparoscopic ultrasonography directly influenced surgical management in four (31%) cases; three by detection of small focal masses and one by exclusion of masses suspected on CT portography. Laparoscopic ultrasonography provided guidance for biopsy or added important anatomic information in three cases. Laparoscopic ultrasonography was complementary to CT portography but added no additional information in three cases, and it failed to provide any information in two cases. Laparoscopic ultrasonography was falsely negative in one case. In this preliminary series, laparoscopic ultrasonography assisted surgeons in critical decision-making by either providing important new information, clarifying questionable areas, or complementing CT portography.