Aspergillus terreus is a rarely reported pathogen in humans, Recovery of this organism from the sputum may therefore be discounted as representing contamination this report describes 3 patients--1 with allergic bronchopulmonary aspergillosis (ABPA), 1 with aspergilloma, and 1 with infective endocarditis-- in whom A. terreus was proved to be the etiologic organism. Together, these 3 cases span the spectrum of disease usually associated with A. fumigatus. Detection of serum precipitins against Aspergillus is essential to a diagnosis of both ABPA and aspergilloma. In our 2 patients with these syndromes, serum precipitins were specific for A. terreus ane did not cross-react with A. fumigatus or mixed Aspergillus antigens. This finding suggests that screening of serum for precipitins were specific for A. terreus and did not cross-react with A. fumigatus or mixed Aspergillus antigens. This finding suggests that screening of serum for precipitins should be carried out with A. terreus antigen in patients suspected of harboring this organism.