Leukocyte subsets in peripheral blood, which include neutrophils, lymphocytes, and monocytes, have not been well established as prognostic factors in patients with hepatocellular carcinoma (HCC). Consecutive patients who underwent curative hepatic resection for HCC at the National Cancer Center, Republic of Korea, from 2001 to 2008 were enrolled in this retrospective study. Clinicopathologic factors, cancer-specific survival (CSS), and disease-free survival (DFS) were analyzed with respect to preoperative lymphocyte subsets, especially monocyte ratio. The 603 patients had a median follow-up of 40.0 months and a 5-year overall survival rate of 67.7 %. In univariate analysis of survivals, preoperative lymphocyte ratio a parts per thousand currency sign35 % and monocyte ratio > 7 % were significantly poor prognostic factors. In multivariate analysis, preoperative monocyte ratio > 7 %, satellite nodule, and microvascular invasion were independent risk factors for CSS and DFS (hazard ratio of monocyte ratio > 7 % = 1.77, p = 0.02 and 1.57, p = 0.006, respectively). Considering monocyte ratio with preoperative alpha-fetoprotein level, patients with both abnormal alpha-fetoprotein levels (> 12 ng/mL) and monocyte ratio > 7 % showed significantly worse CSS and DFS than other groups (p < 0.001). Cirrhotic patients with monocyte ratio > 7 % showed significantly poor CSS and DFS compared with non-cirrhotic patients (p = 0.033 and < 0.001, respectively). A preoperative monocyte ratio > 7 % of peripheral blood is an independent risk factor for CSS and DFS after hepatic resection for HCC. Preoperative monocyte ratio might be considered as a novel biomarker for HCC.