The intensive care unit (ICU) is a dynamic, complex and, at times, highly stressful work environment that involves ongoing exposure to the complexities of interprofessional team functioning. Failures of communication, considered examples of poor collaboration among health care professionals, are the leading cause of inadvertent harm across all health care settings. Evidence suggests effective interprofessional collaboration results in improved outcomes for critically ill patients. One recent study demonstrated a link between low standardized mortality ratios and self-identified levels of collaboration. The aim of this paper is to discuss determinants and complexities of interprofessional collaboration, the evidence supporting its impact on outcomes in the ICU, and interventions designed to foster better interprofessional team functioning. Elements of effective interprofessional collaboration include shared goals and partnerships including explicit, complementary and interdependent roles; mutual respect; and power sharing. In the ICU setting, teams continually alter due to large staff numbers, shift work and staff rotations through the institution. Therefore, the ideal ‘unified’ team working together to provide better care and improve patient outcomes may be difficult to sustain. Power sharing is one of the most complex aspects of interprofessional collaboration. Ownership of specialized knowledge, technical skills, clinical territory, or even the patient, may produce interprofessional conflict when ownership is not acknowledged. Collaboration by definition implies interdependency as opposed to autonomy. Yet, much nursing literature focuses on achievement of autonomy in clinical decision-making, cited to improve job satisfaction, retention and patient outcomes. Autonomy of health care professionals may be an inappropriate goal when striving to foster interprofessional collaboration. Tools such as checklists, guidelines and protocols are advocated, by some, as ways for nurses to gain influence and autonomy in clinical decision-making. Protocols to guide ICU practices such as sedation and weaning reduce the duration of mechanical ventilation in some studies, while others have failed to demonstrate this advantage. Existing organizational strategies that facilitate effective collaboration between health care professionals may contribute to this lack of effect.