BACKGROUNDS/AIMS: Gas-forming pyogenic liver abscess (GFPLA) has an incidence of up to 30% of all pyogenic liver abscesses (PLA). GFPLA has higher mortality compared to non-GFPLA. Mere presence of gas within abscess may not determine clinical outcome. Hence it is important to study biologic characteristics that make GFPLA a distinct clinical entity. The aim of this study was to conduct a world review on GFPLA. METHODS: We conducted literature searches in PubMed using the following MeSH terms: "gas forming" AND "Liver abscess, pyogenic", "gas" AND "Liver abscess, pyogenic", "gas" AND "Liver abscess", "gas forming" AND "Liver abscess". Thirteen case series including 313 GFPLA patients were included. Age, gender, diabetes mellitus (DM), bacteriology, underlying etiology, symptoms, investigations, operative indications, and mortality rates were tabulated. RESULTS: is the most common causative pathogen. GFPLA has higher mortality compared to non-GFPLA (mean: 30.3% vs. 9%). CONCLUSIONS: infection. GFPLA has high mortality. It needs to be recognized as a distinct clinical entity.