Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder caused by hypersensitivity to Aspergillus fumigatus which primarily complicates the course of asthma and cystic fibrosis. There is a theoretical possibility that patients with chronic obstructive pulmonary disease (COPD) can also develop Aspergillus hypersensitivity (AH) and/or ABPA. The aim of this prospective case-control study conducted in the Chest Clinic was to evaluate the prevalence of AH/ABPA in patients with COPD. Two hundred subjects with COPD (17, 62, 74, 47; GOLD guidelines stages I-IV respectively) and 100 healthy volunteers were screened with an Aspergillus skin test. Patients were said to have AH if they demonstrated immediate cutaneous hyperreactivity to A. fumigatus antigen and those with positive responses were further investigated for ABPA. Of this patient population there were 179 (89.5%) males and 21 (10.5%) females with a mean age of 57.1 in the COPD arm and 88 males and 12 females with a mean age of 52.3 in the control arm. AH was found in 17 (8.5%) patients with COPD as compared to none in the control group. Two (1.0%) COPD patients fulfilled the serologic criteria for the diagnosis of ABPA. On univariate analysis, age of the patient, duration of COPD, smoking index and the COPD severity did not predict the occurrence of AH. On the basis of this study we concluded that AH/ABPA can occur in patients with COPD, and it is probable that COPD could be a predisposing factor for AH/ABPA. The clinical significance of AH and ABPA in COPD remains unclear.