OBJECTIVES:  Multiple sclerosis (MS) is the neurologic disability that can dramatically affect the quality of life (QoL) of patients and their families. Family life, economic status, and social interaction may be affected by somatic symptoms of the disease. Approximately 70,000 people in the Islamic Republic of Iran are affected by MS. Under budgetary constraints,Cost-effectiveness and cost-utility analyses (CEA/CUAs) are  useful tools to assess the tradeoff between the added costs and potential benefits (e.g., improved patient outcomes) of new  therapies. METHODS:  The primary objective of this analysis was to evaluate the cost-effectiveness of Avonex compared with Betaferon from the Iranian Ministry of Health(MoH) over a 2-year time horizon. The relative risk reduction (RRR) method was used to compare reduction in relapse rates and disease progression data from pivotal randomized double-blind placebo-controlled clinical trials of the DMDs. The evaluation was conducted from the perspective of a Iranian health care sector (direct medical costs and indirect cost considered). The primary economic endpoint was cost per relapse avoided . Costs and outcomes occurring in the second year were discounted 3% to bring to 2010 present values. One way sensitivity analyses were conducted on key input variables to assess their impact on cost per relapse avoided. RESULTS: The 2-year reductions in clinical relapses for treatment with Avonex,Betaferon were 0.69 and 0.60 relatively. In the base case analysis, Avonex had the most favorable costs per relapse avoided (2652778 Rials) rather than Betaferon. Sensitivity analyses showed that these results were robust to changes in key input parameters, such as the number of relapses and disease progression steps in untreated patients, the progression rates, the average cost of relapse. CONCLUSIONS:  This evaluation suggests that IFN β-1a SC injection(Avonex) represent the most cost-effective DMDs for the treatment of RRMS, where cost-effectiveness is defined as cost per relapse avoided,rather than Bataferon.