Scedosporium aurantiacum is an opportunistic filamentous fungus frequently isolated from the sputum of cystic fibrosis patients in Australia.  At the moment, very little is known about the infection mechanism of S. aurantiacum. Secreted proteases have been shown to contribute to fungal virulence, as demonstrated in the studies with e.g. Aspergillus fumigatus and Candida albicans, in which secreted proteases have been found to cause tissue damage or compromise proteins involved in immune response. Here we compared the profiles of secreted proteases between a high-virulence cystic fibrosis clinical isolate WM 06.482 and a low-virulence environmental strain WM 10.136, in shake flask cultivations. The results showed that proteases secreted by the clinical strain consisted predominantly (over 80%) of elastase-like and trypsin-like serine proteases. Aspartic type proteases were responsible for 10% of the total protease activity and other aminopeptidases together formed the last 10%. Overall, the activity of the elastase-like, trypsin-like and aspartic proteases was from 5 to 50 fold higher (depending on the protease type) in the clinical strain compared to the environmental strain.  Therefore, it suggests that these classes of proteases may contribute to the virulence of Scedosporium. Protease activity of the two strains was further studied by zymogram gel assays. The results indicated two protease bands, with molecular weights of approximately 26 kDa and 60 kDa respectively, were produced by the clinical strain only.  The corresponding proteins were identified as a C78 family peptidase and an aspartyl aminopeptidase by mass spectrometry, searched against all existing fungal database in GPM. Upon availability of the Scedosporium genome sequence, we plan to isolate genes responsible for the synthesis of proteases, specifically those produced by the clinical strain.