The present study aims to examine the relationship between polymorphisms in the third intron of the IFN-γ gene and their influence on susceptibility to multiple sclerosis. A population-based case-control study was used for this purpose. Multiple sclerosis patients and healthy controls were interviewed. Genetic polymorphisms of IFN-γ intron III at the +2118 A/G and +3586 G/ACT sites were detected using polymerase chain reaction-restriction fragment length polymorphism. Genotypes and allele frequencies of IFN-γ intron III at the +2118 position were significantly different between multiple sclerosis patients and controls (P ≥ 0.05). However, no difference in allele frequencies was observed at the +3586 position between the two groups (P ≤ 0.05). Thus, polymorphisms at the +2118 A/G site in the IFN-γ intron III gene may be associated with susceptibility to multiple sclerosis.