Phenotypic features and sequences of the internal transcribed spacer (ITS) regions and the 5.8 S rRNA gene of type or neotype strains and other isolates of the 17 species currently assigned to Aspergillus section Circumdati and some potentially related species were analyzed. Parsimony analysis of sequence data indicated that Aspergillus section Circumdati is paraphyletic. Aspergillus campestris, A. lanosus, and A. dimorphicus with A. sepultus were found to be more closely related to Aspergillus sections Candidi, Flavi, and Cremei, respectively. These results were also supported by phenotypic data. A. robustus and A. ochraceoroseus were found not to be related to any of the species examined. Species of the proposed revised Aspergillus section Circumdati formed two main clades, which could also be distinguished based on phenotypic methods. Phylogenetic analysis of sequence data of other isolates assigned to species of the revised section indicates that either some of these isolates were misidentified or species concepts of A. ochraceus, A. melleus, and A. petrakii should be reconsidered.