Background: The comparison of prognosis between right and left-sided colon cancer (RC, LC) has recently attracted a lot of attention. We examined whether primary location of colo-rectal cancer represents a prognostic factor of patients received curative resection of liver metastasis. Methods: We reviewed all patients undergoing resection of liver metastasis of colo-rectal cancer from1992 to 2013 in the 2 YCU hospitals, and selected eligible 377 patients (59 [15.6 %] with RC, 318 [84.4 %] with LC) undergoing R0 or 1 resection of primary and metastatic lesions. Patients with transverse colon cancer were excluded. We stratified patients according to previously-reported prognostic factors of hepatic metastasis resection, and conducted univariate analysis by Log Rank test to compared overall survival (OS) in each stratum. Using those results, independent factors affecting OS were determined by multivariable Cox regression. Results: The median OS of 377 patients was 66 months, and disease free survival (DFS) was 11.6 months. Univariate analysis revealed that the number and maximum diameter of liver metastasis, existence of other metastasis apart from liver, CEA, and having pre- or post- operative chemotherapy showed significant difference of OS. Primary site did not show significant difference of OS (p = 0.547), but median OS of LC (67 months) was 24 months longer than of RC. As for DFS, there was no significant difference between RC and LC (10.75 vs. 11.6 months, p = 0.873). Multivariate Cox regression analysis was conducted using former factors showing significant difference and primary site. Then primary site was an independent prognostic factor (p = 0.047). LC showed a lower risk than RC (HR: 0.675). Conclusions: The primary site did not affect DFS, but could become a prognostic factor of OS with patients undergoing curative resection of liver metastases. It suggested that curative resection of liver metastases could contribute to prolong survival, regardless of RC or LC. And there is some possibility that the primary site affects prognosis after post-operative recurrence of colo-rectal cancer liver metastases.