Ideally, treatment recommendations are based on the results of multiple, or at least duplicate, adequately powered, randomized controlled trials in patients with demographics similar to those of the target population. The substantial costs of large pharmacotherapy trials generally require sponsorship by pharmaceutical firms anticipating substantial financial rewards from the marketing of new, effective drugs. These elaborate trials are costly and, in the absence of an expectation of profit, impractical to undertake for relatively uncommon conditions such as infections due to nontuberculous mycobacteria (NTM). MAC lung disease is one of these uncommon conditions that is treated with off-patent medications and requires prolonged treatment courses and follow-up. All of these factors have significantly limited treatment trials to date, and, as a result, guidelines for the treatment of NTM infections are based largely on uncontrolled case series, retrospective data, and expert opinion.