BACKGROUND: Atrial fibrillation (AF) is a common arrhythmia in the ICU. The aim of this review is to summarize relevant information on new-onset AF in non-cardiac critical illness with respect to epidemiology, prevention, and treatment. METHODS: We conducted a PubMed search in June 2014 and included studies describing the epidemiology, prevention, and treatment of new-onset AF and atrial flutter during ICU stay in non-cardiac adult patients. Selected studies were divided into the three categories according to the extracted information. The methodological quality of selected studies was described according to the Grading of Recommendations Assessment, Development and Evaluation system. RESULTS: We identified 1,132 citations, and after full-text-level selection, we included 10 studies on etiology/outcome and five studies on treatment. There was no study related to prevention. Overall quality of evidence was mostly low or very low due to their observational study designs, small sample sizes, flawed diagnosis of new-onset AF, and the absence of mortality evaluation. The incidence of new-onset AF varied from 4.5% to 15.0%, excluding exceptional cases (e.g., septic shock). Severity scores of patients with new-onset AF were higher than those without new-onset AF in eight studies, in four of which the difference was statistically significant. Five studies reported risk factors for new-onset AF, all of which used multivariate analyses to extract risk factors. Multiple risk factors are reported, e.g., advanced age, the white race, severity scores, organ failures, and sepsis. Hospital mortality in new-onset AF patients was higher than that of patients without AF in all studies, four of which found statistical significance. Among the five studies on treatment, only one study was randomized controlled, and various interventions were studied. CONCLUSIONS: New-onset AF occurred in 5%-15% of the non-cardiac critically ill patients. Patients with new-onset AF had poor outcomes compared with those without AF. Despite the high incidence of new-onset AF in the general ICU population, currently available information for AF, especially for management (prevention, treatment, and anticoagulation), is quite limited. Further research is needed to improve our understanding of new-onset AF in critically ill patients.