Noninvasive liver imaging has developed rapidly resulting in increased accuracy for detecting primary and secondary hepatic tumors. Intraoperative ultrasonography (IOUS) was commonly considered to be the gold standard for liver staging, but the current value of IOUS is unknown in view of more sophisticated radiologic tools. The purpose of this prospective study was to evaluate the impact of IOUS on the treatment of 149 patients undergoing liver surgery for malignant disease (colorectal metastasis, 61 patients; hepatoma, 52 patients; other hepatic malignant tumors, 36 patients). The sensitivities of computed tomography (CT), helical CT, magnetic resonance imaging, and IOUS in patients with colorectal metastases were 69.2%, 82.5%, 84.9%, and 95.2% in a segment-by-segment analysis; in patients with hepatoma their sensitivities were 76.9%, 90.9%, 93.0%, and 99.3%; and in patients with other hepatic malignancies they were 66.7%, 89.6%, 93.3%, and 98.9%, respectively. Additional malignant lesions (AMLs) were first detected by inspection and palpation in 20 patients (13.4%). In another 18 patients (12.1%) IOUS revealed at least one AML. Overall, the findings obtained only by IOUS changed the surgical strategy in 34 cases (22.8%). It was concluded that IOUS, having undergone some refinement as well, still has immense diagnostic value in hepatectomy candidates. Frequently avoiding palliative liver resection and occasionally disproving unresectability as assessed by preoperative imaging, IOUS still has a significant impact on surgical decision making and should still be considered the gold standard.