Non-invasive ventilation (NIV) is a supportive therapy that improves mortality in acute respiratory failure (RF). It may also be used in patients recently extubated in intensive care units (ICUs), after operation, and to aid weaning from mechanical ventilation (MV) by reducing the morbidity and mortality associated with further MV. A meta-analysis of the available evidence was performed on the use of NIV in three areas: weaning, reduction in reintubation rates post-extubation on ICU, and reduction in RF after major surgery. Sixteen relevant randomized controlled trials were identified by three reviewers after a detailed search of identified medical databases. A meta-analysis of summary statistics relating to predetermined endpoints (ICU and hospital length of stay, ICU and hospital mortality, reintubation, pneumonia) was performed. NIV reduced the ICU length of stay when used for weaning (5.12 days) and post-surgery (0.44 days). NIV reduced reintubation rates post-surgery [odds ratio (OR) 0.24, 95% confidence interval (CI) 0.12-0.50] and the incidence of pneumonia in weaning (OR 0.12, 95% CI 0.05-0.31) and post-surgery (OR 0.27, 95% CI 0.09-0.77). There was insufficient evidence to suggest that NIV improves ICU survival, but an increased hospital survival in weaning (OR 0.55, 95% CI 0.31-0.98) and post-surgery (OR 4.54, 0.95% CI 1.35-15.31) was seen. A meta analysis of NIV use in selected subgroups of recently extubated patients suggests that the judicious NIV use may reduce ICU and hospital length of stay, pneumonia, and reintubation rates and hospital survival.