Objective: To evaluate the economic impact of buprenorphine/naloxone (B/N) as an agonist opioid treatment for opiate dependence. Methods: A budgetary impact analysis model was designed to calculate the annual costs (drugs and associated costs) to the Spanish National Healthcare System of methadone versus B/N. Data for the model were obtained from official databases and expert panel opinion. Results: It was estimated that 86,017 patients would be in an agonist opioid treatment program each of the 3 years of the study. No increase in the number of patients is expected with the introduction of B/N combination. The budgetary impact (drugs and associated costs) for agonist opiate treatment in the first year of the study would be 89.53 million EUR. In the first year of B/N use, the budgetary impact would rise by 4.39 million EUR (4.6% of the total impact), with an incremental cost of 0.79 million EUR (0.9% of the total impact). The budgetary increase would be 0.6% (0.48 million EUR increase) and 0.6% (0.49 million EUR increase) in the second and third years of use, respectively. The mean cost per patient in the first year with and without B/N would be EUR 1,050 and 1,041, respectively. The most influential variables in the sensitivity analysis were logistics and production costs of methadone and the percentage use of B/N. Conclusion: With an additional cost of only EUR 9 per patient, B/N is an efficient addition to the therapeutic arsenal in the drug treatment of opiate dependence, particularly when considering clinical aspects of novel pharmacotherapy.