The 32-base pair deletion on the C-C chemokine receptor 5 gene (CCR5-delta 32) is known as a protective allele against immune system disorders. We have studied this variation in Iranian multiple sclerosis (MS) patients and healthy controls. DNA samples were prepared from the whole blood of 254 patients with MS and 380 healthy controls. We amplified the fragment including the CCR5-delta 32 polymorphism and visualized the products in a documentation system after agarose gel electrophoresis. Data were analysed using one-way ANOVA and Fisher's exact tests with SPSS-v13 and STATA-v8 software. The delta 32 allele was more frequent in MS patients when compared with controls (OR = 2.3, P < 0.0001). Also, we found a significant difference in the frequency of the delta 32/delta 32 genotype among patients and controls (OR = 7.4, P < 0.001). The mean age at onset and progression index was not significantly different between patients with various genotypes. According to our study, the delta 32 allele of the CCR5 gene might be a predisposing factor for MS development in the Iranian population. However, there were no associations between this polymorphism and the clinical course of the disease in this study.