Previous COPD prevalence rates are highly variable. This high variability probably depends on different criteria and methods used. The actual impact of COPD is probably underestimated. Measures of the burden of COPD, such as morbidity, mortality, and costs are based on these prevalence rates, and thus underly the same challenges. The GOLD strategies, published in 2001, established objectifiable physiological criteria to define prevalence and severity of COPD. These guidelines will enhance the quality of prevalence rates and the burden of COPD in the near future. Until now only a few epidemiological studies considered these criteria. The present review outlines current findings on COPD risk factors, COPD burden and recent results of the international Burden of Obstructive Lung Disease study (BOLD).