OBJECTIVES To estimate budget impact analysis (BIA) of belimumab plus standard of care (SoC) comparing the SoC alone in the treatment of patients suffering from systemic lupus erythematosus (SLE). METHODS BIA was conducted of the belimumab treatment plus SoC vs SoC alone. Costs of treatments in both groups contained following direct medical costs: costs of drugs and administration, costs of diagnostic laboratory and instrumental procedure, costs of inpatient and outpatient visits, costs of SLE complications and also adverse event costs. A five-year time horizon was used. All costs in both groups were estimated to their present value using a 5 % discount rate. RESULTS Costs of the course of belimumab therapy were 2,118,449 RUB/ 45,581 EUR for 5 years but the difference in the required budget funds between belimumab treatment groups and SoC alone treatment group amounted to 1,876,965 RUB/ 40,385 EUR for 5 years with a 5 % discount rate. The decrease of the difference in the required budget funds between these two groups was due to a lower frequency of inpatient visits and pulmonary, cardiovascular, renal and skin complications of SLE in group treated with belimumab. Therefore the use of belimumab led to a reduced difference in the required budget funds from 2,118,449 RUB/ 45,581 EUR to 1,876,965 RUB/ 40,385 EUR and the reduction ran as high as 241,484 RUB/ 5,196 EUR for 5 years. CONCLUSIONS The use of belimumab in the treatment of patients with SLE resulted in budget spending. However, a good safety profile and efficacy of belimumab help reduce the costs for 241,484 RUB/ 5,196 EUR for 5 years in belimumab treatment group.