['Mixed Cryoglobulinemia (MC) represents the most frequent extrahepatic manifestation of chronic Hepatitis C Virus (HCV) infection. Its pathogenic mechanisms involve HCV-induced chronic stimulation of B-lymphocytes. We aimed to investigate the relationship between serum levels of vitamin D (a regulator of immune response) and the presence of serum cryoglobulins in the setting of HCV infection.', 'We evaluated the serum concentration of 25(OH)vitamin D and cryoglobulins in 106 patients with chronic HCV infection.', 'Thirty patients (28.3%) showed the presence of serum cryoglobulins. For the cohort overall, the median serum 25(OH)vitamin D level was 10.95 ng/ml. Patients with serum cryoglobulins had significantly lower levels of 25(OH)vitamin D (5.61 ng/ml) than those without (13.65 ng/ml, p=0.029). At multivariate analysis, severe hypovitaminosis [i.e. 25(OH)vitamin D <13 ng/ml] was the only independent predictor of cryoglobulinemia (odds ratio=3.108).'] Are low vitamin D levels associated with the presence of serum cryoglobulins in patients with chronic HCV infection?