Abstract:In this retrospective investigation from Malmö, a city well‐suited for epidemiologic studies, 177 patients (88 males and 89 females) with polycythemia vera (PV) were identified between 1950 and 1984. The incidence rate (number of cases/100 000/yr) in both sexes increased significantly, being 1.0 in 1950–1959 and 2.6 in 1980–1984 (adjusted to the European age‐standardized population). This is the highest rate reported to date. In 1970–1984 the highest age‐specific incidence rates (number of cases/100 000/yr) were found in males ≥ 80 yr and females 70–79 yr of age, being 18.3 and 14.6, respectively. A subgroup of 12 (7%) was identified where the PV diagnosis was not obvious on entry into the study but where it became clear during follow‐up. 16 PV patients (9%) had verified or suspected arterial hypoxemia caused by a concomitant condition. We conclude that the increasing PV incidence rates, mainly confined to older age groups, are probably due to better