INTRODUCTIONInflammatory bowel diseases (IBD) are relapsing and remitting chronic intestinal disorders with extra-intestinal manifestations (EIM). IBD predominantly consist of two different clinical forms: Crohn's disease (CD) and ulcerative colitis (UC) (1,2).Anemia is a common complication in IBD and has a known negative impact not only on quality of life and but also on the ability to work (3,4). Thus, the detection and treatment of anemia in IBD patients deserves careful consideration with regards to the approach (5). Anemia of chronic disease (ACD) and iron deficiency anemia (IDA) are major causes of anemia in IBD patients (5,6). Vitamin B 12 and/or folate deficiency and drug-induced bone marrow suppression may represent other important contributing factors (7). In cross-sectional studies of IBD series, anemia was reported over a very wide range, from 6% to 74% (8,9). Indeed, the frequency of anemia differs among IBD patient populations and is dependent on hospitalization, IBD type, and remission status. Anemia has been reported to be more frequent in hospitalized patients and CD patient groups but less frequent in patients with clinical remission. In a recent review, the mean prevalence of anemia in an IBD patient population was 17% (16% in outpatients and 68% in hospitalized patients), with anemia occurring more frequently in patients with CD than in patients with UC (5,8). However, scarce information is available regarding the incidence rate of anemia over time in IBD cohorts. The anemia prevalence of Turkish IBD patients is also unknown.The main aim of this study was to determine the incidence rate and distribution of anemia types over time in an IBD patient cohort spanning 18 years from a single tertiary center in Turkey. Conclusion: This is the first study to report the incidence rate of anemia (103.45 per 1,000 patient-years) in a longterm cohort of IBD patients.