The objective of the study is to investigate the impact of anemia (defined as hemoglobin concentration of <12 g/dl in women and 13 g/dl in men) on prognosis and to study the effect of recovery from anemia on echocardiographic and clinical parameters in patients with aortic stenosis (AS). This was a prospective study in 315 patients with moderate or severe AS. Patients with anemia received oral iron (ferrous sulfate with mucoproteose, 160 mg iron/day) and erythropoietin, if needed, or intravenous iron, if necessary. The following tests were performed before and after normalization of hemoglobin values: echocardiogram, 6-minute walk test, N-terminal B-type natriuretic peptide, and measures of depression, cognitive impairment, and dependence. Patient mean age was 74 years (SD 9). Mean follow-up was 25 months (SD 8). Anemia prevalence in the overall group was 22% (n = 70). Patients who are anemic had a higher rate of complications at follow-up (mortality, hospital admission, or need for valve procedure; 80% vs 62%, p = 0.009). In total, 89% of patients recovered from anemia, with a mean time to recovery of 4.6 weeks (SD 1.4). Improvements were observed on echocardiographic parameters of peak velocity (4.1 to 3.7 m/s, p = 0.02) and mean gradient (44 to 35 mm Hg, p = 0.02). Performance on the 6-minute walk test improved from 235 to 303 m (p <0.001). Median N-terminal B-type natriuretic peptide value decreased from 612 to 189 pg/dl (p <0.001). In conclusion, patients with AS and anemia have a worse prognosis than those without anemia. Resolution of anemia is associated with improvements in echocardiographic parameters and functional status, suggesting that treatment of iron deficiency is a relevant option in the management of patients with AS, particularly in nonoperable cases.