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, pyogenicâ€, “gas†AND “Liver abscess, pyogenicâ€, “gas†AND “Liver abscessâ€, “gas forming†AND “Liver abscessâ€. 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: GFPLA is often cryptogenic. There was no difference in age, gender, or symptomatology between GFPLA and non-GFPLA patients. DM was more common in patients with GFPLA compared to that in non-GFPLA patients (mean: 83.5% vs. 38.3%). Klebsiella pneumoniae is the most common causative pathogen. GFPLA has higher mortality compared to non-GFPLA (mean: 30.3% vs. 9%). CONCLUSIONS: GFPLA is associated with DM and monomicrobial Klebsiella pneumoniae infection. GFPLA has high mortality. It needs to be recognized as a distinct clinical entity.