OBJECTIVES: To assess the economic impact of Fentanyl Buccal Tablet for the management of breakthrough cancer pain (BTcP) in Spain  METHODS: A 4-year budget impact model was developed for the period 2012-2015 for patients with BTcP from the perspective of the Spanish National Health System. BTcP products included in this model were rapid onset opioids containing fentanyl products (buccal, sublingual, or nasal transmucosal). Prevalence data on cancer, BTcP, opioid use and number of BTcP episodes were obtained from literature. Input data on direct medical resources associated with opioid use and opioide-induced side effects (OISEs) were obtained by consulting experts in oncology from different Spanish hospitals. Resource utilisation included drugs, medical and emergency visits, other non-pharmacological treatments and the treatment of OISEs. Unit costs were obtained from literature and a 3% discount rate was applied to costs. Based on the unit costs for drugs and medical resources the annual BTcP treatment costs per patient associated with each product were determined, to estimate the overall budget impact based on the total treatment population and the percentage of drug utilisation associated with each product  RESULTS: Patients treated with oral opioids for BTcP was estimated at 23,291 in 2012 with an increase up to 23,413 in 2015. The average annual budget savings with an increase of Fentanyl Buccal Tablet, Fentanyl Sublingual Tablet and Intranasal Fentanyl Spray and a decrease of Oral Transmucosal Fentanyl Citrate, was estimated at €2.6 million over the next four years CONCLUSIONS:   The increase in the use of Fentanyl Buccal Tablet leads to overall savings in the budget impact for the Spanish NHS. Although the economic impact of BTcP treatment showed to increase over the next four years due to population growth the average annual cost per patient reduced with €29 by the increase in the use of Fentanyl Buccal Tablet.