We investigated the diagnostic utility of Aspergillus galactomannan (GM) in sputum for diagnosis of invasive pulmonary aspergillosis (IPA) in haematologic patients and compared the results with those of bronchial lavage fluid (BLF) and serum. Patients were classified into 4 groups using modified European Organization for Research and Treatment of Cancer criteria: group A, proven IPA; group B, probable IPA; group C, possible IPA; group D, others. Groups A and B were considered the IPA group (n = 6); group D was considered non-IPA group (n = 37); group C (n = 13) was equivocal for IPA. As a true negative control, sputa from patients with community-acquired pneumonia (CAP) without risk factors (group E, n = 22) were used. From the receiver-operating characteristic curves, the cut-off levels were determined as 1.2 in sputum, 0.5-1.3 in BLF and 0.5 in serum. The sensitivity and specificity of sputum, BLF and serum GM were 100 and 62.2%, 66.7 and 100%, and 83.3 and 81.1%, respectively. Twenty-two patients with CAP (group E) showed median GM levels in the sputa of 0.1 (range 0.0-1.0). Sputum GM is a useful non-invasive test for screening of IPA in haematological patients, and may also be useful for assessment of the risk of developing IPA.