During the complex interaction between host immune cells and infectious microorganisms, modulation of host cell death (apoptosis) often determines the progression and outcome of an infection. The opportunistic human pathogenic fungus Aspergillus fumigatus , the most common cause of invasive aspergillosis in patients with severely impaired immunity, has been reported to either ind uce or inhibit host cell apoptosis depending on its distinct morphological form. However, the detailed mechanism of apoptosis inhibition mediated by A. fumigatus conidia remains elusive and the impact on survival of alveolar macrophages, the prominent resi dent phagocytic cells in the alveolar tract that control early steps of disease development, has not been studied thus far.