BACKGROUND: There is conflicting evidence on the impact of liver disease (CFLD) on life expectancy in CF. Therefore the aim of this systematic review was to evaluate the impact of liver disease (CFLD) on mortality in CF. METHODS: The protocol was published at (https://hrbopenresearch.org/articles/3-44/v3) using PRISPMA-P guidelines and registered in Prospero 2020 (CRD42020182885). Three databases were searched for publications (1938-2020) where the outcome was all-cause mortality (defined as death and transplantation) or CF-specific mortality in participants with CFLD. Studies with and without a comparator group were included. Studies were divided into 2 groups based on the definition of CFLD: Group 1 used 2 categories of liver disease (i) liver disease with portal hypertension (PH) (ii) non-specific abnormalities which did not meet the criteria for PH, Group 2 studies only included participants with PH. RESULTS: All 14 eligible studies were observational, with a moderate-high risk of bias, Six of the 14 studies directly compared mortality between those with CFLD and those with no liver disease, and 5/6 demonstrated that those with CFLD had at least 3 time the risk of death compared to those with no liver disease. Pulmonary complications were the primary cause of death. CONCLUSION: This SR demonstrates that liver disease shortens life expectancy in CF, and that pulmonary complications are the primary cause of death in those with CFLD. There has been no improvement in survival for persons with CFLD despite significant improvements in life expectancy for persons with CF who have no evidence of liver disease.