Invasive fungal infections due to Aspergillus species have become a major cause of morbidity and mortality among immunocompromised patients. Aspergillus terreus, a less common pathogen, appears to be an emerging cause of infection at our institution, the University of Alabama hospital in Birmingham. We therefore investigated the epidemiology of A. terreus over the past 6 years by using culture data; antifungal susceptibility testing with amphotericin B, voriconazole, and itraconazole; and molecular typing with random amplification of polymorphic DNA-PCR (RAPD-PCR). During the study period, the percentage of A. terreus isolates relative to those of other Aspergillus species significantly increased, and A. terreus isolates frequently were resistant to amphotericin B. Molecular typing with the RAPD technique was useful in discriminating between patient isolates, which showed much strain diversity. Further surveillance of A. terreus may better define epidemiology and determine whether this organism is becoming more frequent in relation to other Aspergillus species.