Summary. The objectives of this article were to study the reported prevalence of haemophilia B (HB) on a country-by-country basis and to analyse whether the prevalence of HB varied by national economy. The prevalence of HB is the proportion of diagnosed, reported cases of HB in a population at a specific point of time. We collected data on the HB prevalence for 105 countries from the World Federation of Hemophilia annual global surveys. Our results showed that the HB prevalence varied considerably among countries, even among the wealthiest of countries. The HB prevalence (per 100 000 males) for the highest income countries was 2.69 ± 1.61 (mean ± SD), whereas the prevalence for the rest of the world was 1.20 ± 1.33 (mean ± SD). Ireland had the highest reported HB prevalence of 8.07 per 100 000 males. There was a strong trend of increasing HB prevalence (per 100 000 males) over time. Prevalence data reported from the WFH compared well with prevalence data from the literature. The WFH annual global surveys have some limitations, but they are the best available source of worldwide haemophilia data. Prevalence data are extremely valuable information for the planning efforts of national healthcare agencies in setting priorities and allocating resources for the treatment of HB.