When the adjacent organ is partially invaded by a hepatocellular carcinoma (HCC), whether to go on an aggressive resection is a difficult but challenging problem. To investigate the worth of en bloc resections, a retrospective controlled study was conducted. During a 9-year period, nine patients (seven men, two women: group I) who had HCC with invasions to extrahepatic adjacent organs had undergone en bloc resections. The adjacent organs included diaphragm (eight cases), adrenal gland (two cases), abdominal wall (one case), and spleen (one case). The patients selected for en bloc resections were those with a solitary tumor without evidence of vascular invasion or intravascular tumor thrombi, daughter nodule(s), or distant metastasis. The evidence was based on preoperative evaluation by ultrasonography, computed tomography, arteriography, and intraoperative ultrasonography. Eighteen matched patients with HCC but no involvement of neighboring organs were selected as controls (14 men, 4 women: group II). Though patients of group I had wider invasion of HCC and more extensive resection, their surgical morbidity, mortality, hospital mortality, disease-free interval, and survival time were similar to those of group II, who had more limited HCC and resections. Eighteen months after operation, the HCC recurrence rate was 44% and 41% in groups I and II, respectively, and the percent survivals were 71% and 63%, respectively. We suggest that in cases of large HCC with local invasion to neighboring organs, aggressive en bloc resection is recommended after appropriate patient selection.