ABSTRACT: BACKGROUND:Memory gaps in intensive care unit (ICU) survivors are associated with psychiatric disorders. The ICU diaries improve the patient's factual memory of the ICU, but it is not clear if they reduce the incidence of psychiatric disorders in patients and relatives after hospital discharge. The aim of this study is to evaluate the literature on the effect of ICU diaries for patients admitted in ICU and their relatives. METHODS:Two authors independently searched the online databases PubMed, OVID, Embase, EBSCO host, and PsycINFO from inception to July 2019. Studies were included if the intervention group (ICU diary) was compared with a group with no diaries and the sample was comprised patients ??18?years old admitted in the ICU for more than 24?h and their relatives. Randomized clinical trials, observational studies, letter with original data, and abstracts were included, irrespective of the language. The search was not limited by any specific outcome. Review articles, commentaries, editorials, and studies without a control group were excluded. Structured tools were used to assess the methodological quality ("Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I)" for cohort studies and the "Cochrane Risk of Bias tool" for included RCTs and before/after studies). A random-effects model was employed considering the anticipated variability between the studies. RESULTS:Seven hundred eighty-five titles were identified for screening. Two additional studies were selected after a reference search, and after a full-text review, a total of 12 studies were included. When pooling the results, ICU diary was associated with lower risk of depression (RR 0.41, 95% CI 0.23-0.75) and better quality of life (10.3 points higher in SF-36 general health score, 95% CI 0.79-19.8), without a decrease in anxiety or post-traumatic stress disorder (PTSD). For the relatives receiving an ICU diary, there was no difference in the incidence of PTSD, anxiety, or depression. CONCLUSION AND RELEVANCE:This systematic review and meta-analysis supports the use of ICU diaries to reduce the risk of depression and preserve the quality of life of patients after ICU admission. ICU diaries do not seem to have any beneficial effect on the relatives of the patients. TRIAL REGISTRATION:PROSPERO, CRD42019136639.