Introduction: Predicting extubation outcome and preventing extubation failure is an important task. We hypothesized that patients who fail a trial of weaning develop diaphragmatic fatigue. The prediction rate of various weaning parameters may not be satisfactory. Accordingly we suggest that ultrasonographic evaluation of diaphragmatic excursion during spontaneous breathing trials may be a good predictor for extubation outcome. Objective: The aim of the work was to determine the value of diaphragmatic motion measured by B- mode of chest ultrasound as a predictor tool for discontinuation of patients from mechanical ventilation. Patients and Methods: The patients (60 patients) were classified into a success group (SG) or failure group (FG) according to the extubation outcome. Weaning parameters including RSBI, VTspon, and maximum inspiratory Force were measured and ultrasonographic measurement of diaphragmatic excursion was performed within 6 h before extubation. The maximal liver and spleen displacements among 10 respiratory cycles were recorded. The final mean value of liver displacement and spleen displacement (MD) was calculated. Results: The present study included 60 patients, 48 of whom (80%) were in the SG and 12 patients (20%) FG. The baseline data were similar for these two groups. All the weaning parameters were significantly better in the SG and highest significance with the diaphragmatic movement also recorded. Using a cutoff value of 1 cm, the sensitivity and specificity to predict successful extubation were 95.2% and 88.9%, respectively, better than traditional weaning parameters in this study. Conclusion: It is obvious that diaphragmatic movement more sensitive and specific parameter than volume associated weaning parameter in predicting extubation outcome. Assessment of diaphragmatic movement measured by real time ultrasonography is a good predictor of extubation outcome.