Results: Out of 216 sputum samples, 145 (67.1%) were positive for fungal growth. Furthermore, out of 264 grown fungal colonies, 137 (51.9%) were Aspergillus species. Among the Aspergillus isolates, A. flavus (29.2%) was the most prevalent species, followed by A. fumigatus (27.7%). The mean forced expiratory volume in one second (FEV1) in the mild, moderate and severe asthmatic patients with a positive sputum culture for fungi were obtained as 90.0 ± 11.1, 71.1 ± 15.9 and 54.9 ± 16.4, respectively. In general, Aspergillus species colonisation had no statistically significant effect on spirometry results of study patients.