Background: Communication among doctors, nurses, and families contributes to high-quality end-of-life care, but is difficult to improve. Objective: Our objective was to identify aspects of communication appropriate for interventions to improve quality of dying in the intensive care unit (ICU). Methods: This observational study used data from a cluster-randomized trial of an interdisciplinary intervention to improve end-of-life care at 15 Seattle/Tacoma area hospitals (2003)(2004)(2005)(2006)(2007)(2008). Nurses completed surveys for patients dying in the ICU. We examined associations between nurse-assessed predictors (physician-nurse communication, physician-family communication) and nurse ratings of patients' quality of dying (nurse-QODD-1). Results: Based on 1173 nurse surveys, four of six physician-nurse communication topics were positively associated with nurse-QODD-1: family questions, family dynamics, spiritual/religious issues, and cultural issues. Discussions between nurses and physicians about nurses' concerns for patients or families were negatively associated. All physician-family communication ratings, as assessed by nurses, were positively associated with nurse-QODD-1: answering family's questions, listening to family, asking about treatments patient would want, helping family decide patient's treatment wishes, and overall communication. Path analysis suggested overall physician-family communication and helping family incorporate patient's wishes were directly associated with nurse-QODD-1. Conclusions: Several topics of physician-nurse communication, as rated by nurses, were associated with higher nurse-rated quality of dying, whereas one topic, nurses' concerns for patient or family, was associated with poorer ratings. Higher nurse ratings of physician-family communication were uniformly associated with higher quality of dying, highlighting the importance of this communication. Physician support of family decision making was particularly important, suggesting a potential target for interventions to improve end-of-life care.