Background: Leukemia is cancer of the blood or bone marrow, characterized by an unusualincrease in white blood cells. It is the sixth most common malignancy in the country in bothmales and females. The aim of this study was to document some epidemiological features ofleukemia in the Northwest of Iran.Methods: The study subjects (n=669, including 377 males and 292 females) comprised allleukemia cases registered/notified to the clinical and pathology centers of Tabriz and Ardebilcities, from 2003 to 2006. All patients were classified using the ICD-10 based coding system(C91-C95, C77 and C42). Ninety-five percent confidence intervals were calculated to assessthe statistical significance of the data.Results: Annual incidence of leukemia was 3.7 [95% CI: 3.3–4.0] and 4.9 [95% CI: 4.2–5.6]per 100 000 population in Tabriz and Ardebil, respectively, with an overall case fatality rateof 13.5 percent [95% CI: 10.8–16.0]. The sex ratio (male/female) was 1.23. Myeloid leukemia(C92) and Hematopoetic and Reticuloendothelial system (C42) accounted proportionally formore than 47 percent of cases in the region. Over the study period, the annual occurrence ofleukemia in the region increased from 3.9 [95% CI: 3.4–4.5] to 4.1 [95% CI: 3.5–4.6] per 100000 population (P>0.1).Conclusions- The data from this cross-sectional study of leukemia in the North-West of Iranmay be used as the baseline information to establish a population-based registry of hematologicdisorders in the area for health care and research purposes. However, more investigationsare needed to develop effective strategies to control the relevant disorders in high-riskgroups
