Chronic obstructive lung disease (COPD) primarily affects men; however, its epidemiology has been changing because more women have become smokers. Recently, investigators found that although women and men were exposed to the same amount of smoke fume, women tended to have more severe disease and higher mortality rate. They also complain of more dyspnoea and may experience more severe exacerbations than men. This led to the question of whether sex has an impact on COPD course and whether women have a higher susceptibility to smoke fumes than men. That may be explained by multiple complex factors highlighting the relationship between sex, epidemiology, method of diagnostics and the clinical course of the disease.