Several studies demonstrated that intraoperative ultrasonography (IOUS) represents the gold standard among the liver imaging studies in detection the neoplastic nodules, so that its routinary use is claimed either during resection of primitive than metastatic hepatic tumorsIn the present experience the role of IOUS in detection of lesions missed by preoperative imaging is investigated. Material and Methods. IOUS was performed under surgeon's demand in 68 out of 123 patients (55%) undergone to liver resection for cancer(38 primitive, 30 metastatic). Results. In this series IOUS was able to identify additional lesions in 3 out 38 patients (8%)with hepatocellular carcinoma (HCC) and 4 out off 30 cases (13%) of metastatic adenocarcinoma.These lesions were undiagnosed both by preoperative radiologic examinations and by surgical exploration.IOUS also confirmed the presence of doubttil nodules or correctly showed the location of previously diagnosed but invisible and non palpable lesions in 9 out of 38 (23%) HCC patients and in 1 out of 30 (3%)patients with metastases. Conclusions. US intraoperative screening of liver tumors may be mandatory both to avoid blind resections with sacrifice of health parenchyma in cirrhosis, and the leak of additional primitive or metastatic lesions. IMO 1407 PERCUTANEOUS ULTRASOUND-GUIDED CATHETER DRAINAGE OF LARGE SPLENIC