Purpose- To evaluate whether spontaneous breathing trials (SBTs) are necessary when extubating critical care patients. Methods- A prospective, randomized, double-blind study was performed in adult patients supported by mechanical ventilation for at least 48 hours in the general intensive care unit of a teaching hospital. Patients ready for weaning were randomly assigned to either the SBT group (extubation with an SBT) or the no-SBT group (extubation without an SBT). Patients in the SBT group who tolerated SBT underwent immediate extubation. Patients in the no-SBT group who met the weaning readiness criteria underwent extubation without an SBT. The primary outcome measure was a successful extubation or the ability to maintain spontaneous breathing for 48 hours after extubation. Results- A total of 139 adult patients were enrolled. No significant difference in the demographic, respiratory, and hemodynamic characteristics was indicated between the groups at the end of weaning readiness assessment. Successful extubation was achieved in 56 of 61 patients (91.8%) in the SBT group and 54 of 60 patients (90.0%) in the no-SBT group. In the SBT and no-SBT groups, 5 (8.2%) and 6 (10.0%) patients, respectively, needed reintubation; 7 (11.5%) and 9 (15.0%) patients, respectively, required noninvasive ventilation after extubation. In-hospital mortality did not differ significantly between the groups. Conclusion- Intensive care patients can be extubated successfully without an SBT.