Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory neuronal damages and consequent disabilities. Episodic relapses of the disease which lead to brain lesions and irreversible neurological dysfunctions could be decreased by the interferon-beta (IFN-β) therapy in most of the MS patients. However, the efficiency of the drug response is highly variable among patients and the precise mechanism of action of the IFN-β is not clear. To investigate the role of RORA gene as a biomarker of patient's responsiveness, the present study have analyzed the frequency of two polymorphisms (rs4774388 and rs11639084) within this gene between responder (n = 105) and nonresponder (n = 65) groups of MS patients in comparison with 200 healthy controls. The tetra primers-Amplification Refractory Mutation System-PCR method was used for genotyping. The obtained result of the current study showed a significant association between nonresponsiveness and the rs4774388 in dominant model (p = 0.03). However, the allele and genotype frequencies of rs11639084 were not different between controls, nonresponder, and responder patients. In addition, the frequencies of the estimated haplotype blocks were not different between examined groups. The obtained results of the present study suggested the rs4774388 as a possible effective factor in determination of response to IFN-β. However, further studies are needed to confirm the results in a larger sample size.