Abstract Objective To evaluate the diagnostic accuracy of diaphragmatic ultrasound in predicting extubation success. Design A diagnostic accuracy study was carried out. Scope Intensive Care Unit of an Academic hospital in the city of Bogotá (Colombia). Patients or participants A consecutive sample of patients > 18 years of age subjected to invasive mechanical ventilation for > 48 h. Interventions Diaphragmatic ultrasound evaluation at the end of spontaneous ventilation testing. Main variables of interest Diaphragmatic excursion (DE, cm), inspiration time (TPIA dia , s), diaphragm contraction speed (DE/TPIA dia , cm/s) and total time (Ttot, s) were evaluated, together with thickening fraction (TF di , %). Results A total of 84 patients were included, 79.8% (n = 67) with successful extubation and 20.2% (n = 17) with failed extubation. The variable with the best discriminatory capacity in predicting extubation success was diaphragm contraction speed, with AUC-ROC 0.70 (p = 0.008). Conclusions Diaphragm contraction speed exhibited acceptable discriminatory capacity. Ultrasound could be part of a multifactorial approach in the extubation process.