To compare volume- and pressure- controlled ventilation (VCV-PCV) as an initial ventilatory mode in chronic obstructive pulmonary disease (COPD) patients. Case-control study conducted in respiratory intensive care unit (RICU) at a large teaching hospital, between January 2002 and January 2004. PCV was applied in 20 COPD patients with ARF more than 24 hours. Their outcomes were compared with those of a control group of 20 COPD patients matched on age, sex, Acute Physiology Assessment and Chronic Health Evaluation (APACHE) II score, pH and PaCO(2) at the time of intubation previously treated with VCV. The effectiveness of matching was 99%. Groups were compared according to complication and mortality rates, total duration of invasive mechanical ventilation (IMV) and length of RICU stay. Mortality and complication rates, and length of RICU stay were similar in groups but, the mean duration of MV was longer in PCV (198 +/- 177 h vs. 79 +/- 56 h, p< 0.003). PCV group spended significantly longer IMV hours for weaning period (138.6 +/- 164 vs. 34 +/- 33 h, p< 0.01), pre-weaning periods of IMV were found similar. These data suggest that both ventilatory approach have similar outcomes in COPD patients with ARF. Randomize-controlled trials are needed to confirm our results.