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Species assigned to Aspergillus section Versicolores are commonly isolated from different indoor environments. Due to a great variation in macrophenotypic characteristics and only few in microphenotypic, DNA based phylogenetic study elucidated appropriate assignement of isolates to this section. Previously, Aspergillus versicolor was the most commonly reported species isolated from indoor air of damp indoor environment and a major contributor to sick building syndrome described as a complex of respiratory dissorders among inhabitants of damp dwellings. One of incriminating factors in such conditions is a high frequency of sterigmatocystin (STC) producers among the isolates assigned to this species. Moreover, its presence is confirmed in building materials such as wall scrapes, house dust and grain dust. Although mechanisms are not completely understood and clarified, significant toxic properties of STC are confirmed on various cell cultures and animal models. The purpose of our research was to examine the distributon of isolates assigned to section Versicolores in indoor air in Croatia and to test their capability of STC biosynthesis. We included samples isolated from indoor environments including basements, apartments and grain mill. A polyphasic approach including sequence-based methods, morphological and physiologicyal examinations and mycotoxin producing abilities was used for species identification. Accordingly, we identified following species: A. jensenii (22), A. creber (13), A. venenatus (4), A. tenneesseensis (1), A. amoenus (5), A. griseoaurantiacus (1) and Aspergillus section Versicolores spec. nov. (3). All samples examined were capable of sterigmatocystin production as confirmed in associated microextracts by HPLC/UV-Vis methods. Highest contents of STC were found in samples belonging to A. jensenii ranging from 1.192 μg/mL to 133.63 μg/mL while the lowest concentration of STC were detected in extracts of A. protuberus in range of 0.117 to 2.749 μg/mL and A. tenneseensis which was 0.871 μg/mL. STC was detected in 13/25 dust samples collected in grain mill (0.06 μg/g to 2.35 μg/g). This research confirmed variability in species assigned to section Versicolores and underlined the actual and possible presence of STC in selected indoor environments.