Value of preoperative diagnostic procedures in the surgical treatment of liver tumors. Results of a consecutive examination series from surgical view. Between September 1985 and December 1988 93 patients with tumors of the liver were operated at the University Hospital of Mainz. Most of them had metastases of colorectal cancer. The accuracy of preoperative diagnostic proceedings was very high using abdominal ultrasonography and computed tomography. The sensitivity of both methods for detecting a tumor amounts 88 and 95%. In spite of this high accuracy the intraoperative findings were different in 29% of the treated patients. An unfavourable intraoperative situation did not exclude a radical resection of the tumor. Therefore we think that the indication to operation is correct if there is any doubt about the expansion of the tumor.