BACKGROUND: Clinically assisted hydration (CAH) can be provided in the last days of life as drinking declines. The impact of this practice on quality of life or survival in the last days of life is unclear. Practice varies worldwide concerning this emotive issue. METHOD: Systematic literature review and narrative synthesis of studies evaluating the impact of, or attitudes toward, CAH in the last days of life. Databases were searched up to December 2019. Studies were included if the majority of participants were in the last 7 days of life, and were evaluated using Gough's 'Weight of Evidence' framework. Review protocol registered with PROSPERO, registration number CRD42019125837. RESULTS: Fifteen studies were included in the synthesis. None were judged to be both of high quality and relevance. No evidence was found that the provision of CAH has an impact on symptoms or survival. Patient and family carer attitudes toward assisted hydration were diverse. CONCLUSION: There is currently insufficient evidence to draw firm conclusions on the impact of CAH in the last days of life. Future research needs to focus on patients specifically in the last days of life, include those with non-malignant diagnoses, and evaluate best ways to communicate effectively about this complex topic with patients and their families.