Invasive fungal infections are an increasingly common problem in cancer patients and in other vulnerable groups. Invasive pulmonary aspergillosis (IPA) in the neutropenic host presents particular challenges in terms of diagnosis and therapy. Against the background of a recognized problem of invasive aspergillosis in haematology/oncology patients treated at the Christie Hospital, we undertook a prospective study in patients at risk for IPA. The aim of the study was to improve outcome by using the linked strategies of first, early diagnosis, and secondly, early aggressive therapy with a lipid-associated formulation of amphotericin B, amphotericin B colloidal dispersion ('Amphocil'). Early investigation comprised the use of high-resolution computerized tomography scanning of the thorax and fibreoptic bronchoscopy to obtain bronchoalveolar lavage specimens, processed using conventional detection and culture methods. Using this approach, the incidence of proven or probable IPA in patients with acute leukaemia was 9%. Prompt initiation of amphotericin B colloidal dispersion therapy led to a successful outcome in 11 of 13 patients, compared with a mortality of 100% in historical controls.