Background: Over the last 20 years, multiple interventions to better integrate palliative care and intensive care unit (ICU) care have been evaluated. This systematic review summarizes these studies and their outcomes. Methods: We searched MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature (CI-NAHL), the Cochrane Library, and the Web of Science; performed a search of articles published by opinion leaders in the field; and reviewed hand-search articles as of August 13, 2012. The terms ''palliative care'' and ''intensive care unit'' were mapped to MeSH subject headings and ''exploded.'' We included trials of adult patients that evaluated an ICU intervention and addressed Robert Wood Johnson group-identified domains of high-quality end-of-life care in the ICU. We excluded case series, editorials, and review articles. We compared two types of interventions, integrative and consultative, focusing on the outcomes of patient and family satisfaction, mortality, and ICU and hospital length of stay (LOS), because these were most prevalent among studies. Results: Our search strategy yielded 3328 references, of which we included 37 publications detailing 30 unique interventions. Interventions and outcome measures were heterogeneous, and many studies were underpowered and/or subject to multiple biases. Most of the interventions resulted in a decrease in hospital and ICU LOS. Few interventions significantly affected satisfaction. With one exception, the interventions decreased or had no effect on mortality. There was no evidence of harm from any intervention. Conclusions: Heterogeneity of interventions made comparison of ICU-based palliative care interventions difficult. However, existing evidence suggests proactive palliative care in the ICU, using either consultative or integrative palliative care interventions, decrease hospital and ICU LOS, do not affect satisfaction, and either decrease or do not affect mortality.