The objective of this article was to estimate the medical costs derived from malignant ARD treatment in the Spanish National Health System (NHS) between 2004 and 2011. Estimation of direct healthcare costs was based on national primary data on the cost of specialized care for inpatients and outpatients treated at NHS hospitals and on national and regional secondary data on costs of primary healthcare and pharmaceutical prescriptions. A prevalence approach was used to estimate the overall burden of ARDs. Direct medical costs of 37,557 ARDs attended in Spanish NHS facilities in 2004–2011 were estimated at 464 million euros; specialist care accounted for 50.9% of total costs, primary healthcare 10.15%, and drug prescription 38.9%. The cost was 27.8-fold higher in males than in females. Bronchopulmonary cancers represented the greatest healthcare cost, 281 million euros. The cost of delivering healthcare to ARDs victims in Spain has a negative economic impact on the NHS due to the gross under-recognition of occupational victims under the Spanish National Insurance System.