In recent years, several lines of evidence have questioned the asexual nature of Aspergillus fumigatus, showing that this fungus possesses a fully functional sexual reproductive cycle that leads to the production of cleistothecia and ascospores. The presence of a sexual cycle in A. fumigatus could have significant medical implications, as sexual reproduction might contribute to increased virulence or resistance to antifungal agents. In the present work, we studied the relationship between mating type and invasiveness in A. fumigatus. Statistical analysis of the results showed a significant association between the mating type MAT1-1 and an invasive origin of the isolates. Similarly, when the clinical or environmental origin of isolates was considered instead of their invasive or non-invasive origin, a significant association between the mating type MAT1-1 and clinical origin was observed. Finally, the association between mating type MAT1-1 and pathogenicity, measured by an Elastase Activity Index > or = 1, was significant. Our results suggest a possible association between the MAT1-1 mating type and A. fumigatus invasiveness.