Liver resection is the only potentially curative method for patients with colorectal cancer metastases and 5-year survival rates are 20%-40%. Simultaneous resection of colorectal cancer and synchronous liver metastases has been recommended if minor hepatectomy is indicated. The purpose of this paper is to analyze the treatment of hepatic colorectal secondaries and to assess the safety of simultaneous and delayed liver resections and relations of morbidity to the extensiveness of hepatectomy and perioperative factors. Analyzed were 21 patients with liver metastases from colorectal cancer operated between 1997 and 1999 in the Clinical Hospital "Sestre milosrdnice". Operating time for simultaneous colorectal and liver resections was not significantly longer compared to liver resections alone. No significant difference in complication rate was found after simultaneous procedures and liver resection alone (38% vs. 31%). Complication rate after major liver resections was not significantly greater than after minor resections (38% vs. 31%). No statistically significant differences were found in operation time and blood replacement between patients who developed postoperative complications and those who did not. In conclusion, simultaneous resections of primary colorectal cancer and liver metastases may be considered safe. Morbidity rates are not significantly different from those after liver resections alone, nor depend significantly upon the extensiveness of liver resection, providing that the operation time and blood loss are within the range observed in this study.