Background Invasive aspergillosis (IA),which is mainly caused by Aspergillus fumigatus (A.fumigatus),is a major cause of morbidity and mortality in immunocompromised patients.Despite considerable progress in currently available antifungals the mortality still remains high in critically ill patients.U0126 which is a highly selective inhibitor of MEK1 and MEK2 in the RAF/MEK/ERK pathway in mammalian cells has been demonstrated to have an anti-proliferative role in cancer cells.The purpose of this study was to explore the role of U0126 on growth inhibition and activation of mitogen-activated protein kinases (MAPKs) in A.fumigatus.Methods Germination percentage and hyphae growth in A.fumigatus treated with U0126 were observed and compared with untreated controls.West blotting analysis was used to detect changes in activation of SakA,MpkA and MpkB.Results U0126 inhibited germination and hyphae growth in A.fumigatus and enhanced the phosphorylation of SakA and MpkA under oxidative stress.U0126 at 10 μmol/L did not block the activation of MpkB during nitrogen starvation stress.Conclusion U0126 shows promise as an antifungal candidate and the MAPK pathway may be a possible antifungal drug target for A.fumigatus.