Systemic inflammation was recognized as an essential factor contributing to the development of malignancies. This study aimed to investigate the prognostic value of pre-operative lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) in patients with colorectal liver-only metastases (CLOM) undergoing hepatectomy. We retrospectively enrolled 150 consecutive patients with CLOM between 2000 and 2012. The optimal cutoff values of continuous LMR, NLR, and PLR were determined using the receiver operating characteristic curve analysis. Recurrence-free survival (RFS) and overall survival (OS) related to the LMR, NLR, and PLR were analyzed using both Kaplan-Meier and multivariate Cox regression methods. Elevated LMR (>= 2.82) and lower NLR (< 4.63) were significantly associated with better RFS and OS in patients with CLOM after hepatectomy, instead of lower PLR (< 150.17). Multivariate Cox analysis identified elevated LMR as the only independent inflammatory factor for better RFS (hazard ratio, 0.591; 95% CI, 0.32-0.844; P=0.008) and OS (hazard ratio, 0.426; 95% CI, 0.254-0.716; P=0.001). In the subgroup analysis, elevated LMR was a significant favorable factor in both 5-year RFS and OS of patients with male gender, lymph node metastases, colon cancer, liver tumor with the largest diameter,5 cm, preoperative carcinoembryonic antigen level,200 ng/mL, negative hepatitis B virus infection, non-anatomic liver resection, postoperative chemotherapy, and non-preoperative chemotherapy. This study demonstrated that the preoperative LMR was an independent predictor of RFS and OS in patients with CLOM undergoing hepatic resection, and it appeared to be superior to the NLR and PLR.