Background: Nurses and physicians often describe critical care that is not expected to provide meaningful benefit to a patient as futile, and providing treatments perceived as futile is associated with moral distress. Objective: To explore concordance of physicians' and nurses' assessments of futile critical care. Methods: A focus group of clinicians developed a consensus definition of "futile" critical care. Daily for 3 months, critical care physicians and nurses in a health care system identified patients perceived to be receiving futile treatment. Assessments and patients' survival were compared between nurses and physicians. Results: Nurses and physicians made 6254 shared assessments on 1086 patients. Nurses and physicians assessed approximately the same number of patients as receiving futile treatment (110 for nurses vs 113 for physicians, P = .82); however, concordance was low as to which patients were assessed as receiving futile treatment (k = 0.46). The 110 patients categorized by nurses as receiving futile treatment had lower 6-month mortality than did the 113 patients so assessed by physicians (68% vs 85%, P = .005). Patients who were assessed as receiving futile treatment by both providers were more likely to die in the hospital than were patients assessed as receiving futile treatment by the nurse alone (76% vs 32%, P <.001) or by the physician alone (76% vs 57%, P = .04). Conclusions: Interprofessional concordance on provision of critical care perceived to be futile is low; however, joint predictions between physicians and nurses were most predictive of patients' outcomes, suggesting value in collaborative decision making.