OBJECTIVE: Liver involvement of SARS-CoV-2 infection has been reported in several papers, but without homogeneous findings. We aimed to systematically review the prevalence of liver involvement in patients with SARS-CoV-2 infection at their hospital admission, and its correlation with disease severity and clinical outcomes in patients with or without pre-existing chronic liver disease. MATERIALS AND METHODS: We systematically searched PubMed, Embase, Web of Science, Medline, PMC, clinical trial registries, and other Coronavirus family publications for studies reporting data on SARS-CoV-2 infection or COVID-19 and liver function tests (LFTs) alterations, as well as clinical course of patients with chronic liver disease or cirrhosis. Case reports, preprints, editorials, reviews were excluded. We also revised literature to describe the background of liver involvement during SARS-CoV-2 infection. RESULTS: 36 studies, including 20724 patients with SARS-CoV-2 infection, were included. The pooled prevalence of LFTs abnormalities at admission was 46.9% (AST 26.5%, ALT 22.8%, GGT 22.5%, ALP 5.7%, tBIL 8.0%). ALT, AST, tBIL were independent predictors of disease severity (ALT OR 1.54, 95% CI 1.17-2.03; AST OR 3.17, 95% CI 2.10-4.77; tBIL OR 2.32, 95% CI 1.18-4.58) and in-hospital mortality (ALT OR 1.48, 95% CI 1.12-1.96; AST OR 4.39, 95% CI 2.68-7.18; tBIL OR 7.75, 95% CI 2.28-26.40). Heterogeneity among studies was high. The few available data also reported that COVID-19 was associated with increased risk of liver decompensation and mortality in patients with liver cirrhosis. CONCLUSIONS: LFTs alterations were reported in up to 47% of unselected patients with COVID-19 and were associated with severe disease or in-hospital mortality. In cirrhotic patients, COVID-19 was associated with high risk of liver decompensation or mortality.