Little is known about the role of Aspergillus precipitating antibody (APAb) in patients with Mycobacterium avium complex lung disease (MAC-LD). We investigated the clinical characteristics of patients with MAC-LD positive for APAb. We conducted a cross-sectional study targeting patients with MAC-LD. APAb was checked in all participants. Clinical variables included laboratory data, pulmonary function, high-resolution computed tomography findings, and health-related quality of life. We analyzed 109 consecutive patients. Their median age was 68 years, and the median duration of MAC-LD was 4.8 years. Twenty (18.3%) patients tested positive for APAb. APAb-positive patients had significantly longer duration of MAC-LD (9.4 vs. 4.0 years, P = 0.017), more severe bronchiectasis evaluated by modified Reiff score (6.5 vs. 4, P = 0.0049), and lower forced expiratory volume in 1 s (%FEV1) (75.1% vs. 86.2%, P = 0.013) than APAb-negative patients. Analysis of covariance adjusted for background factors and underlying pulmonary disease revealed that %FEV1 was also significantly lower in patients with APAb (P = 0.045). Ten patients were newly diagnosed with chronic pulmonary aspergillosis (N = 5) or allergic bronchopulmonary aspergillosis (N = 5). APAb is associated with lower pulmonary function, and observed especially in patients with longer duration of MAC-LD and severe bronchiectasis, even in the absence of cavitary lesions. •18% MAC-LD patients tested positive for Aspergillus precipitating antibody (APAb).•APAb was observed in patients with severe bronchiectasis.•APAb was associated with lower pulmonary function in MAC-LD patients.•9.2% of MAC-LD patients were newly diagnosed as CPA or ABPA.