Liver resection remains the popular treatment for hepatocellular carcinoma (HCC). The aim of this study was to explore the alteration of immune cells in HCC patients with liver resections. Nineteen patients were included and their peripheral blood samples were taken before and after liver resections for immune-cell analysis. The clinical characteristics showed that the median diameter of the resected tumors was 7.5 cm with a range from 1.4 to 16.5 cm. The analysis of immune cells showed that the percentage of CD4+ T-cells were not altered by liver resection, but the percentage of CD8+ T-cell was decreased from 31.7 ± 12.4% to 20.2 ± 10.4% at one week after liver resection (p = 0.006). For immunosuppressor cells, regulatory T-cells were not altered, but myeloid-derived suppressor cells (MDSC) were decreased from 7.75 ± 8.16% to 1.51 ± 1.32% at one month after liver resection (p = 0.022) in 10 of 19 patients with high frequency of MDSC. Furthermore, it was also found that MDSC population was linearly correlated to tumor volume. In conclusion, CD8+ T-cells and MDSC were altered by liver resection. The percentage of CD8+ T-cells was decreased by surgery, but the accumulation of MDSC was abrogated.