In most cases, invasive aspergillosis (IA) is caused byA. fumigatus, though infections with otherAspergillusspp. with lower susceptibilities to amphotericin B (AmB) gain ground.A. terreus, for instance, is the second leading cause of IA in humans and of serious concern because of its high propensity to disseminate and its in vitro and in vivo resistance to AmB. An early differentiation betweenA. fumigatusandnon-A. fumigatusinfections could swiftly recognize a potentially ineffective treatment with AmB and lead to the lifesaving change to a more appropriate drug regime in high-risk patients. In this study, we present the characteristics of the monoclonal IgG1-antibody AB90-E8 that specifically recognizes a surface antigen ofA. fumigatusand the closely related, but not human pathogenicA. fischeri. We show immunostainings on fresh frozen sections as well as on incipient mycelium picked from agar plates with tweezers or by using the expeditious tape mount technique. All three methods have a time advantage over the common procedures currently used in the routine diagnosis of IA and outline the potential of AB90-E8 as a rapid diagnostic tool.