Detection of (1,3)-beta-D-glucan (BDG), a component of the cell wall of many fungi, was studied in bronchoalveolar lavage fluid (BALF) as a possible aid for the diagnosis of proven/probable invasive pulmonary aspergillosis (IPA). BDG was measured on stored BALF from 13 patients with EORTC/MSGERC defined proven/probable IPA and 26 matched control patients without IPA. The median BALF BDG was 80 pg/mL (range < 45-8240 pg/mL) in the IPA cohort and 148 pg/mL (range < 45-5460 pg/mL) in the non-IPA cohort. Using a positive cutoff of ≥ 80 pg/mL, sensitivity was 54% and specificity was 38%. Higher cutoff values led to improvement in specificity but a dramatic decrease in sensitivity. ROC/AUC analysis was unable to identify an optimal cutoff value at which test performance was enhanced: AUC 0.43, 95% CI 0.24-0.63. When the BDG assay was performed on BALF, neither sensitivity nor specificity was sufficient for use in the diagnosis of IPA.