Anemia, leukopenia and thrombocytopenia are frequent complications of anorexia nervosa. The complete blood count provides useful information to diagnose and characterize these findings. Anemia tends to be normocytic and normochromic. Leukopenia manifests as a deficiency of lymphocytes or neutrophils. Thrombocytopenia, if severe, may confer a bleeding risk. A careful history and physical examination should be performed to evaluate for other possible etiologies of cytopenias. Cell line deficiencies related solely to anorexia nervosa often resolve with nutritional rehabilitation. Knowledge of these potential findings and their expected outcomes may help avoid costly and potentially invasive procedures in patients with anorexia nervosa.