OBJECTIVES: ExTRACT-TIMI 25 is a prospective randomized trial of 20,479 patients with 1,279 recruited in Spain. The use of enoxaparin as adjunctive therapy for fibrinolysis in patients with ST-segment elevation myocardial infarction versus unfractionated heparin (UFH) resulted in a 17% relative risk reduction of death or non-fatal myocardial infarction (MI). Using results from the ExTRACT-TIMI 25 trial we conducted an economic evaluation to estimate the cost-effectiveness of enoxaparin in Spain.   METHODS: Cost-effectiveness analysis was performed from the Spanish National Health Service perspective. Health resource data were obtained from the ExTRACT-TIMI 25 trial, coding according to Diagnostic Related Groups (DRGs). Medical direct costs data (procedures and drugs) were obtained from published Spanish literature. Survival and life expectancy were estimated from the Framingham Heart Study. Results are presented as incremental cost per life year gained (LYG) and cost per Quality Adjusted Life Years (QALY). To prove the robustness of the results we calculated 95% confidence intervals for both costs and results. Long-term costs were discounted at 3% annually after the first year. RESULTS: Considering short-term treatment results (30 days), enoxaparin achieved better results with more LYG than UFH but there was a not significant difference in total costs. The incremental cost-effectiveness ratio for enoxaparin obtained from the 30 days analysis was €977.5/LYG. When long-term (lifelong) analysis was performed the cost obtained was of €2755.6/LYG and €3442.3/QALY CONCLUSIONS: Considering the usual “willingness to pay” cost-effectiveness threshold in Spain (€30,000 per LYG and per QALY) enoxaparin administered as adjunctive therapy for fibrinolysis in ST-elevation myocardial infarction patients is a potentially cost-effective strategy compared with UFH in Spain.