Chronic Obstructive Lung Disease (GOLD) recently defind COPD as “a common preventable and treatable disease characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. Exacerbations and comorbidities contribute to the overall severity in individual patient”. This is an open label, comparative, analytical and prospective study done in the Department of Respiratory Medicine, New Medical College Hospital, Kota during period Oct. 2014 to Sept. 2015. On the basis of history, clinical examination and various investigation 200 study cases of COPD were taken from Respiratory medicine OPD & ward. The aim of study to evaluate the correlation between oxygen saturation and BMI in stable COPD patients. The diagnosis was established by a detailed history, clinical examination followed by chest X- ray & Spirometery. ln our observations, most of patient’s, 55% were undernourished, 37.5% patients had normal BMI, 6% patient was overweight and only 1.5% patients were obese. The relationship between BMI and COPD stage was explored multidimensionally.