Background: In chronic obstructive pulmonary disease (COPD) patients the alveoli do not ventilate fully due to bronchial obstruction. This leads to the incomplete ventilation, incomplete clearance of carbon dioxide causing hypercapnia. There are some muscular abnormalities also in COPD patients. All these pathogeneses lead to type 2 (hypercapnic) respiratory failure. The aim of this study was to determine the frequency of type II respiratory failure in patients with COPD. Methods: This descriptive cross-sectional study was conducted at Department of Medicine, Hayatabad Medical Complex, Peshawar from 21st Aug 2021 to 20th Feb 2022. A total of 129 patients with COPD were enrolled. COPD was diagnosed based on clinical findings and confirmation with spirometry showing FEV1/FVC less than 70% of predicted. Confirmation of type II respiratory failure was done by Arterial-blood gas (ABG) test on heparinized arterial blood sample analysis showing hypercapnia (Paco2 ?45 mmHg). Results: Type II respiratory failure was observed in 31 patients (24%); 19 (22.9%) patients with type respiratory failure had age more than 55 years. Eight (36.4%) patients with type II respiratory failure had GOLD stage 4 COPD. Age of the patients ranged from 40 to 65 years with mean age 53.410±9.362 years. Male to female ratio was 2.4:1. Conclusion: Type 2 respiratory failure is more prevalent in elder patients above 55 years of age, and is more common among males. The severity of COPD does not appear to have a direct relationship with the occurrence of type 2 respiratory failure. Pak J Physiol 2024;20(1):33-6