Despite modern imaging techniques evaluation of the resectability of large focal liver lesions is often difficult or impossible until the time of operation. Based on experience with 54 primary or secondary focal liver tumours, a simple morphological classification has been found to be reasonably predictive of resectability. All tumours were classified before operation using computed tomography, ultrasound and angiography; 38 patients underwent laparotomy. Dependent, 'hanging' tumours (n = 7) were resected in six cases, expansively growing 'pushing' tumours (n = 19) were resected in 18 cases, and infiltrating, 'invasive' tumours (n = 17) were not resected because of involvement with major vascular structures. Eleven small tumours (less than 5 cm) were not classifiable by this system. This simple classification may be a useful clinical concept in preoperative assessment of resectability of focal liver lesions. Hanging tumours should always be resected, and large expansile tumours are generally resectable despite their size. Invasive tumours can only be resected in exceptional cases.