Mechanical ventilation is one of the most common medical therapies administered within ICUs. Similarly, the "weaning" or "liberation" of patients from mechanical ventilation is a common and extremely important task performed in ICUs and specialized ventilator units within hospitals. Various methods exist for assessing a patient's readiness to be liberated from mechanical ventilation and for conducting the weaning process. Clinicians working in ICUs frequently develop their own personal preferences regarding the best approach to weaning patients from ventilatory support. Therefore, variability in the practice of weaning patients from mechanical ventilation is frequently demonstrated, even within a single ICU. Recently, several randomized clinical trials have produced conflicting results regarding the best technique for carrying out the weaning process (e.g., spontaneous breathing trials, intermittent mandatory ventilation, pressure-support ventilation). Such conflicting findings have further illustrated the complexity of the weaning process and the difficulties in identifying the "best" medical practices for carrying out this endeavor. However, other investigations have suggested that the selection of an individual technique for weaning patients from mechanical ventilation may not be as important as employing a systematic approach to this medical process. Protocol-guided weaning of mechanical ventilation in the ICU setting, often performed by nonphysicians, has gained in acceptance as a result of these investigations. We describe the recent experiences of three ICUs which have demonstrated significant improvements in patient outcomes (e.g., shorter durations of mechanical ventilation, lower incidence of ventilator-associated pneumonia, fewer patient complications) as a result of implementing formal weaning protocols. Our hope is that these data will assist other hospitals in developing their own systematic guidelines and protocols for weaning patients from mechanical ventilation.