Breakthrough non- Aspergillus mold infections among patients receiving the anti-mold azole antifungal agents like voriconazole or posaconazole have been increasingly reported. We report a case of lung Scedosporium prolificans infection with multiple cavities in a 58-year-old man with monoclonal gammopathy of undetermined significance (MGUS) during voriconazole treatment for probable invasive aspergillosis. Cultures of repeated sputum specimens yielded the same fungus until his death 83 days after diagnosis. S. prolificans should be considered in patients with breakthrough infections receiving voriconazole.