OBJECTIVE The relationship between multiple sclerosis (MS) and anemia has not been clarified sufficiently. In this retrospective, cross-sectional, case-control study we evaluated in MS patients: (1) prevalence of anemia relative to sex- and age-matched controls; (2) relationships between patients' demographic, clinical and drug-related characteristics and anemia; (3) effect of anemia on the risk of developing MS. METHODS 187 consecutive MS patients (51 males, mean age (±SD) 44.5 ± 10.7 years) and 200 controls (56 males, mean age 45.5 ± 12 years) were included in the study. Anemia was defined as hemoglobin <12 g/dl for females and <13 g/dl for males. RESULTS There was a significant difference in the prevalence of anemia between MS patients and controls (35 (18.7%) and 19 (9.5%), respectively, p = 0.009). We did not find any association between patients' characteristics and anemia. The occurrence of anemia increased more than twice the risk of developing MS (odds ratio: 2.19, 95% confidence interval 1.19-4.0). CONCLUSIONS Our study showed a consistent association between anemia and MS.