Objective: Numerous parameters have been suggested for the prediction of weaning from mechanical ventilation; however, these parameters have limited success in the prediction of weaning outcome. This study aims to assess the success of peak flow rates [spontaneous peak inspiratory flow rate (SPIF) and spontaneous peak expiratory flow rate (SPEF)] that were measured during a spontaneous breathing trial (SBT) for the prediction of weaning outcome. Material and Methods: Patients who were managed and who received mechanical ventilation support for at least 24 h in the Internal Medicine and General Surgery Intensive Care Units of Erciyes University, School of Medicine between March, 2011 and May, 2012 were included in this study. Over 30 min, SPIF and SPEF values were measured during SBT in patients who were spontaneously breathing through a T-tube. Patients who tolerated the 30-min SBT were extubated. Patients who did not require reintubation for 48 h after extubation were considered as successful weaning, whereas those who required re-intubation were considered as weaning failure. Results: The study was completed with a total of 36 patients with 11 patients in the failure group and 25 in the success group. In both the groups, the area under curve (AUC) was calculated for each minute via ROC analysis using minute SPIF and SPEF values that were measured during SBT. The maximum AUC was calculated at 23 min for SPIF (0.564; 95% CI: 0.363–0.764) and at 9 min for SPEF (0.542; 95% CI: 0.316–0.3769). When the cut-off value for SPIF was accepted as >26.7 l/min at 23 min, sensitivity and specificity were calculated as 72.0% and 48.0%, respectively. When the cut-off value for SPEF was accepted as >24.7 l/min at 9 min, sensitivity and specificity were calculated as 63.6% and 48.0%, respectively. Conclusion: We believe that minute SPIF measurement, which has better sensitivity, and minute SPEF measurement, which has better specificity, compared with the available traditional predictors may be used as potential bedside weaning predictors when evaluated in comprehensive studies.