Elevated levels of macrophage migration inhibitory factor (MIF) have been observed in the cerebrospinal fluid of patients with multiple sclerosis. This study was designed to determine if MIF gene polymorphisms are associated with multiple sclerosis and disease severity. In total, 120 relapsing-remitting patients with multiple sclerosis and 120 control subjects were enrolled in the study. There was a statistically significant increase in the MIF -173 CC genotype in patients with multiple sclerosis compared with the control subjects. The MIF -794 6/7 genotype had a significantly lower progression index compared with MIF -794 6/6. Patients with the MIF -173 CC genotype had a significantly lower age of disease onset compared with those with the MIF -173 CG and MIF -173 GG genotypes. Additionally, patients with the MIF -794 5/6 genotype had a significantly later age of disease onset. This study indicates that the MIF -173 CC genotype may cause susceptibility to multiple sclerosis in the white Turkish population and a younger age of disease onset is associated with this polymorphism.