© 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Component ratios that mimic whole blood may produce survival benefit in patients massively transfused after trauma; other outcomes have not been reviewed. The purpose of this review was to systematically analyze studies where clinical outcomes were compared on the basis of the component ratios administered during massive transfusion in adult patients after trauma. PubMed, CINAHL, and MEDLINE (Ovid) were searched for studies published in English between 2007 and 2015, performed at Level I or major trauma centers. Twenty-one studies were included in the analysis. We used an adapted 9-item instrument to assess bias risk. The average bias score for the studies was 2.86 ± 1.39 out of 16, indicating a low bias risk. The most common bias sources were lack of data about primary outcomes and adverse events. Those who received high ratios experienced not only greater survival benefit but also higher rates of multiple-organ failure; all other clinical outcomes findings were equivocal.