As to the epidemiology of myeloproliferative disorders (MPD) very little solid information is available in the literature. The present work attempted to study the incidence of MPD in the city of Göteborg, Sweden during a period of ten years. Therefore, retrospectively we assessed the number of subjects afflicted with polycythaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IM) over the study period of 1983-1992. The yearly calculated incidence for PV was 2.8 per 100,000 population. For ET and IM the corresponding figures were 1.5 and 0.4, respectively. The results for PV demonstrated the highest incidence rate reported in literature so far. As to ET and IM our results largely agree with what has been reported previously in the literature.