BACKGROUND Chronic Obstructive Pulmonary Disease (COPD), a common disease worldwide, refers to two frequently coexisting lung diseases, chronic bronchitis and emphysema. Physiologically, COPD represents a disruption in ventilation and in the exchange of gases in the lungs. Laboratory tests indicate elevated CO2 level, gradual reduction of the levels of oxygen and pH in arterial blood and elevated PeCO2. It does not include other obstructive diseases such as asthma. OBJECTIVE Patients with COPD represent a large portion of those artificially ventilated in an ICU. In an attempt to determine the length of ventilation and stay in ICU, we compared the length of ventilation, weaning, reintubation and discharge during a period of ten months. METHODS This study included 73 patients on mechanical ventilation (MV) due to severe exacerbation of COPD that were not suitable for non-invasive ventilation. Each patient's arterial blood gases (ABG) were measured upon admission and PeCO2 was tested using a Datex S/5 instrument. RESULTS All patients included in the study needed MV; 67 patients were ventilated from 5 to 161 hours (average 40 + 47), 6 patients need more than one week. Three of these patients died due to severe ventilated associated pneumonia. No correlation was found between pH, Pco2 and length of artificial respiration; these findings do not contribute to evaluation of the patient's condition nor do they enable us to predict the length of treatment necessary. CONCLUSIONS Most of the patients (92%) ventilated for acute respiratory failure due to chronic obstructive pulmonary disease (COPD) needed MV for only between 40-47 hours.