OBJECTIVES: Nontuberculous mycobacterial pulmonary disease (NTMPD) is a debilitating rare disease affecting a growing number of individuals worldwide. Treatment consists of a long-term course of multi-drug antibiotic regimen. Patients who are not responsive to first-line therapy have limited therapy options and the cost of their management is unknown. The study objective was to estimate the economic burden of NTMPD, focusing on refractory patients without concomitant cystic fibrosis, who were infected with Mycobacterium Avium Complex (MAC). METHODS: We conducted a retrospective observational survey of physicians in Canada, France, Germany, and the United Kingdom (UK), to collect practice patterns and health care resource utilization among newly diagnosed and existing patients over a 24-month period. Qualified physicians were referred to each patient’s chart to complete an online survey that captured anonymized information about patient’s treatment history for NTMPD-related health care resource utilization. We summarized all NTMPD-related resource use and applied unit costs to estimate the total economic burden. RESULTS: In total, 63 physicians provided data on 182 patient cases. One third of patients had experienced at least one pulmonary exacerbation (PEx) during the 24-month period, and the cost of treating PExs represented between 7 and 15% of total direct medical costs in each country. Hospitalizations for NTMPD, excluding those for PExs, accounted for between 21% and 49% of costs. Outpatient care (e.g. physician visits, testing, pulmonary rehabilitation) comprised between 29 and 65% of costs. In this patient cohort, the average direct medical costs per person-year were $27,100 CAD (Canada), €9,500 EUR (Germany), €13,400 EUR (France) and £13,000 GBP (UK). Cost distributions were right-skewed, with maximum costs up to 9 times the mean costs. CONCLUSIONS: Managing patients with refractory NTMPD caused by MAC is associated with substantial resource use, with annual cost per patient exceeding that for asthma, chronic obstructive pulmonary disease or tuberculosis.