Objective: The appropriate and timely provision of nutritional support to the critically ill hospitalized patient is recognized as an important quality benchmark. However, daily practice is not consistent with best evidence practice. The purpose of this review was to identify and appraise the available evidence to determine whether guidelines for nutritional support can bridge the gap between best evidence and actual practice in the intensive care unit (ICU). Search strategy: Medline (www.PubMed) was searched to detect cluster randomized controlled trials evaluating the benefits of implementing a clinical practice guideline for nutritional support in the ICU. Reference lists of retrieved articles were hand searched. Summary of findings: Three hundred and seventy-six potentially eligible studies were reviewed. Three multi-centre cluster randomized trials were identified. In two of these trials, significant practice change was achieved in the ICU through the active implementation of a clinical practice guideline. In one trial, these improvements in practice translated to a significant reduction in mortality and hospital length of stay. No harm was documented. Conclusions: Evidence-based clinical practice guidelines may be used as a vehicle to change practice and improve patient outcomes in the intensive care unit. Use of a multifaceted practice change strategy, composed of as many specific change interventions as practicable, may be required to overcome ICU-specific barriers to change. © 2010, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.