 The basis of the diagnosis of invasive aspergillosis is usually based on radiological appearances, which are neither sensitive nor specific. The burden of this problem is also not properly documented and there is paucity of prospective data in the literature. Therefore, we want to prospectively collect complete epidemiological data on all our patients. In addition we want to collaborate with radiological, respiratory, and microbiological colleagues to develop a unified approach to diagnosis. In the initial 1218 months of the study all adult haematooncology patients likely to be rendered neutropenic during their treatment will be enrolled. All clinical data will be collected including dose, duration, and sideeffects of antifungals administered. We will evaluate accepted diagnostic modalities for IA including the determination of optimum cutoffs for galactomannan and BDglucan in serum and urine in this cohort. In addition we would investigate the utility of other approaches for the diagnosis of IA such as markers for tissue injury and cytokine profiling. 