Whereas resection for metachronous liver metastases from colorectal cancer is considered to be a potentially curative approach, little is known about the prognosis after resection of synchronous liver metastases. In the past, these patients usually underwent only palliative therapy. Therefore, we have analyzed the data of 36 patients who underwent curative hepatic resection of synchronous liver metastases from colorectal carcinomas from 1977 to 1987 at the Department of Surgery, Hannover Medical School. In 19 patients, liver resection was combined with colonic resection; in the other 17 patients, hepatic resection was performed after a median interval of 2 months following resection of the primary tumor. No operative mortality was observed in either of the approaches. The median survival time was 28 months for all patients with a median recurrence-free interval of 13.5 months. Overall 5-year survival probability for all patients was 20%. There were no significant differences observed between immediate or delayed liver resection (median survival 18 months versus 31 months). Survival rates were not different after resection of solitary versus multiple liver metastases (26 versus 28 months). Twenty-one of the 36 patients had a recurrence of their liver metastases. In 7 of them, curative liver resection could be performed again. These 7 patients had a significantly improved survival (p less than 0.05) compared to the residual 14 patients. It is concluded that patients with synchronous liver metastases from colorectal cancer may profit from resection of the primary tumor and liver metastases. Timing of liver resection--immediate versus delayed--obviously has no impact on survival rates.