INTRODUCTION: According to the Staging System of Barcelona Clinic Liver Cancer (BCLC), diaphragmatic invasion (DI) is generally considered to be a manifestation of advanced hepatocellular carcinoma (HCC) with nearly no cure. However, some studies have indicated that combined liver and diaphragmatic resection may be a reasonably safe treatment option for HCC patients with diaphragmatic invasion. In this article, we conduct a systematic review to compare the short- and long-term surgical outcomes between HCC patients without diaphragmatic involvement who underwent hepatectomy alone and HCC patients with diaphragmatic involvement who underwent combined liver and diaphragmatic resection. EVIDENCE ACQUISITION: PubMed, Web of Science, Embase and Cochrane library databases were searched. All related studies were checked. Hazard ratios (HR) with 95% confidence intervals were calculated for the comparison of cumulative overall survival (OS) and recurrence free survival (RFS). Odds ratios (OR) with 95% CI were calculated for the comparison of overall postoperative morbidity and mortality. EVIDENCE SYNTHESIS: Seven studies met the inclusion criteria were included. There was no significant difference between the single hepatectomy group and combined liver and diaphragmatic resection group in the overall survival and recurrence free survival. Subgroup analysis showed a statistically significantly higher overall survival in HCC patients with diaphragmatic fibrous adhesion (DFA) compared with the DI group. However, there was no statistically significant difference in OS between the DI group and the single hepatectomy group. CONCLUSIONS: For HCC patients with diaphragmatic involvement, combined liver and diaphragmatic resection might be considered no matter whether its diaphragmatic invasion or not.