Abstract Chronic Obstructive Pulmonary Disease (COPD) is a public health problem because it is a major cause of death in the world. Approximately 25% of patients with moderate disease and 35% with severe disease show a reduced fat-free mass (FFM). Thus, the objective of this study is to define the correlation between fat-free mass index (FFMI), muscle function, respiratory symptoms, number of exacerbations during the last year, and degree of airflow obstruction in patients with COPD. It is a prospective and cross-sectional study. The FFMI was below 32.7% (n=18) and the strength diminished by 56.4% (n=31). In the sample, we found a direct and significant correlation between the FFMI and the FEV1 (predicted %), (p= 0.045). When analysed by sex, men had a direct correlation between FFMI and the FEV1 (predicted %), (p=0.019), an inverse correlation between FFMI and the spirometric classification of the Global Initiative Obstructive Lung Disease (GOLD) (p=0.008), and between the muscular function and the symptoms (p=0.03). In women, no significant correlation was found. In conclusion, the conditions in mass and muscular function were correlated with clinical variables and pulmonary function in men. We did not find a correlation between corporal composition and the number of exacerbations.