Based on our observations in chronic obstructive pulmonary disease (COPD) patients admitted to our respiratory intensive care unit due to acute respiratory failure suggesting a significant variation in weaning duration (WD), we conducted a retrospective cohort study in such patients. Fifty-nine patients successfully extubated following invasive mechanical ventilation were included. Syncronized intermittent mandatory ventilation plus pressure support ventilation was used as the weaning mode in mostly. Study population was divided into two groups. Group 1: patients with a WD < or = 24 hours (n= 32), Group 2: patients with a WD > 24 hours (n= 27). Groups were compared with respect to demographics, vital signs, arterial blood gases, laboratory values, and the treatment characteristics. The average WD was 13 +/- 8 and 58 +/- 34 hours in group 1 and group 2, respectively (p< 0.001). In the logistic regression analysis, the following factors were found to have a predictive value for a WD > 24 hours: elevated baseline heart rate, alkaline pH at the day of weaning, duration of midazolam infusion, and emphysematous findings on chest X-ray. In conclusion, whether the WD in COPD patients is less or greater than 24 hours is not only determined by the medical treatment administered, but also by the patient and disease characteristics.