Background: Multiple sclerosis (MS) is a chronic neurodegenerative autoimmune disease mediated by autoreactive T cells against myelin-basic proteins. Cytokines are suggested to play a role in the etiopathogenesis of the disease. Among these cytokines is interleukin-2 (IL-2). Aim of the study: To investigate the association between IL2+166 G/T single nucleotide polymorphism (SNP: rs2069763) and MS in Iraqi patients. Serum level of IL-2 was also detected. Anti-rubella IgG antibody was further determined in the sera of patients. Patients and methods: Eighty MS patients (28 males and 52 females; age mean ± SD: 39.2 ± 16.1 years) and 80 healthy control matched patients for age (32.15 ± 16.13 years) and gender (28 males and 52 females) were enrolled in the study. IL2+166 was detected by conventional polymerase chain reaction using allele-specific primers. Serum status of IL-2 and anti-rubella IgG antibody was determined by enzyme-linked immunosorbent assay. Results: Significantly increased frequencies of IL2+166 GG and GT genotypes were observed in MS patients compared to control (30.0 versus 4.5; odds ratio: 5.29; 95% confidence interval: 2.04–13.72; pc < 0.01 and 55.0 versus 32.5%; odds ratio = 2.54; 95% confidence interval: 1.34–4.81; pc < 0.05 and, respectively). IL-2 level was significantly increased in patients compared to control (36.0 ± 13.3 versus 10.5 ± 5.7 ng/ml). Such level was influenced by IL2+166 genotypes. Twenty-three patients (28.8%) were seropositive for anti-rubella IgG antibody compared to 5% in control. Conclusions: IL2+166 is a susceptibility SNP among Iraqi MS patients. Rubella virus is also suggested to increase the risk of disease.