BACKGROUND: Immunosuppressants are recommended for treatment of autoimmune diseases, and in transplant therapy. The high cost of these drugs has been causing an important impact on global pharmaceutical spending. OBJECTIVE: Analyzing immunosuppressant expenditure in Brazil, using data from the Federal Procurement System database (SIASG), between 2010 and 2015. METHODS: The pharmaceutical products were classified in accordance with the Anatomical, Therapeutic and Chemical (ATC) classification system recommended by World Health Organization (WHO) and aggregated by volume and by expenditure. The expenditure variation was decomposed into three broad categories: price effects, quantity effects, and drug mix effects. RESULTS: During the period, annual expenditure increased by 49%, ranging from USD 494.5 million in 2010 to USD 738.7 million in 2015, while purchased quantities increased by 294%, ranging from 49.8 million in 2010 to 196.5 million in 2015. Two factors drove expenditures: the quantity effect and the drug-mix effect. CONCLUSION: These findings may contribute to understand immunosuppressant spending trends and the factors that influence them in order to formulate effective cost containment strategies and design optimum drug policy. Rigorous evaluations are recommended to reduce the drug-mix effect, including systems to monitor price, effectiveness, safety, therapeutic value and budget impact of pharmaceutical innovations.2025-01-01