OBJECTIVE: To investigate the effectiveness of our method of assisting a cough by mimicking the functions of the glottis in patients with bulbar muscle weakness or paralysis and/or those who had a tracheostomy tube. DESIGN: Before-after trial. SETTING: University rehabilitation hospital. PARTICIPANTS: Patients (N=35) with bulbar muscle weakness or paralysis and/or those who had a tracheostomy tube. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The unassisted peak cough flow (PCF), the assisted PCF, and the assisted PCF with the external control method mimicking glottis function by an end-inspiratory external closure of the airways. RESULTS: Of the 35 patients, 13 were tracheostomized cervical cord injury patients, 11 were neuromuscular disease (NMD) patients with glottis dysfunction only, and 11 were NMD patients with a tracheostomy and glottis dysfunction. Assisted PCF with the external control method were higher than unassisted PCF and/or assisted PCF in all patients. Assisted PCF with the external control methods were measured in all of the patients even when the unassisted PCFs and/or assisted PCFs could not be measured. For patients with measurable assisted PCFs, the assisted PCF with the external control methods were significantly higher than the assisted PCFs. CONCLUSIONS: We showed the effectiveness of our method of assisting a cough by external control of the glottis in patients with bulbar muscle weakness or paralysis and/or those who had a tracheostomy tube who cannot effectively cough with the help of existing cough assistance methods.