Background: The prevalence, characteristic and determinants of anemia, at the time of inflammatory bowel disease (IBD) diagnosis have yet to be fully elucidated. Methods: Retrospective cross-sectional study. Analytical data and disease characteristics obtained upon diagnosis of 1278 IBD patients [Crohn's disease/ulcerative colitis (CD/UC): 718/560] were collected. Results: Anemia was present in 41.2% of patients at diagnosis (47% and 33.8% of CD and UC patients, respectively; p= 2 mg/dL) C-reactive protein (OR 4.08; 95% CI 2.39-6.97 and 4.58; 95% CI 2.26-9.27, respectively). Current smoking was a risk factor for anemia in CD (OR 2.23; 95% CI 1.24-4.02), but a protective one in UC (OR 0.36; 95% CI 0.14-0.92). A penetrating CD behavior increased the risk of anemia (OR 3.34; 95% CI 1.36-8.21); in UC, anemia increased with disease extension (E2 + E3) (OR 1.80; 95% CI 1.13-2.86). Conclusions: Female sex and disease activity are major determinants of anemia at IBD diagnosis. Anemia is associated with disease behavior in CD and with disease extension in UC. (C) 2016 Published by Elsevier Ltd on behalf of Editrice Gastroenterologica Italiana S.r.l.