Diagnosing chronic pulmonary aspergillosis (CPA) is complicated, and there are limited data available regarding the identification of galactomannan (GM) in clinical specimens to assist the detection of this infection. The purpose of this study was to evaluate the detection of GM in bronchoalveolar lavage fluid (BALF) and serum and to assess its utility for diagnosing CPA. We retrospectively reviewed the diagnostic and clinical characteristics of 144 patients, with and without CPA, in Nagasaki University Hospital, Japan, whose BAL and serum specimens were examined for the presence of GM. The Platelia Aspergillus enzyme immunoassay (PA EIA) was performed according to the manufacturer's instructions. The mean values of BALF GM antigen were 4.535 (range, 0.062-14.120) and 0.430 (range, 0.062-9.285) in CPA (18) and non-CPA (126) patients, respectively. The mean values of serum GM antigen were 1.557 (range, 0.232-5.397) and 0.864 (range, 0.028-8.956) in CPA and non-CPA patients, respectively. PA EIA of BALF is superior to the test with serum, with the optimal cut-off values for BALF and serum of 0.4 and 0.7, respectively. The sensitivity and specificity of PA EIA in BALF at a cut-off of 0.4 were 77.2% and 77.0%, respectively, whereas with serum at a cut-off of 0.7, they were 66.7% and 63.5%, respectively. GM testing using BALF showed reasonable sensitivity and specificity as compared to that using serum. Thus, assessing GM levels in BALF may enhance the accuracy of diagnosing CPA.