BACKGROUND: Diaphragm examination by ultrasonography can be used  for evaluating the disease status in COPD patients. The purpose of the present study was to investigate the relationship between diaphragmatic excursion, thickness and spirometry values in COPD patients, using diaphragmatic movements.OBJECTIVES:Primary objective was to compare diaphragmatic thickness and excursion in healthy persons and those diagnosed with COPD and secondary  objective to evolve ultrasound as a diagnostic tool to derive FEV1.MATERIALS AND METHODS: This was a prospective ,observational, cross sectional study conducted among patients with COPD. Sample size was calculated as 70 .All COPD patients and healthy volunteers were subjected to USG of diaphragm.RESULTS .Diaphragm excursion at normal inspiration, deep inspiration, and while sniffing were significantly lower in COPD patients in comparison to healthy controls (P<0.01).Diaphragm thickness at end inspiration, end expiration, and diaphragm thickness fraction were significantly lower in COPD patients in comparison to controls (P<0.01.There was a strong correlation between FEV1 and diaphragm excursion during deep inspiration and sniffing. Through this study we have formulated a linear equation to find out FEV1, that is FEV1 = 2.99 - (0.042 X age) + (0.224 X deep inspiration) + (0.015 X sniffing).