We report three cases of mechanically ventilated chronic obstructive pulmonary disease patients who were intubated due to an exacerbation of their disease and who presented with repeated spontaneous breathing trial failures. Patients were given 50 mg of sildenafil through the nasogastric tube, under close monitoring of haemodynamic and ventilatory parameters. After sildenafil, pulmonary artery pressure, pulmonary artery occlusion pressure, the respiratory frequency to tidal volume ratio and the P(a)CO2-P(ET)CO2 (arterial minus end-tidal carbon dioxide pressure) decreased. Cardiac output increased in two of the patients, while all of them were successfully extubated. This is the first report of successful extubation after sildenafil use.