Abstract. Introduction. Underdiagnosis of late-onset bronchial asthma and improvement of methods for its early detection is an important trend in medicine, which is associated with the increasing number of adult patients with variable respiratory symptoms, allergologic history, and comorbid background. It seems reasonable to improve the early diagnosis of late-onset asthma in comorbid patients using screening scales. Aim. To assess the risk of late-onset bronchial asthma in comorbid patients, using the Adult Epidemiologic Asthma Scale (A2) and the European Community Respiratory Health Survey (ECRHS) questionnaire. Material and Methods. Eighty patients aged 59.9±11.6 (–51.3% of them being female patients) were examined. Group 1: Comorbid patients with the established asthma; group 2: Comorbid patients without asthma. Asthma risk factors, respiratory symptoms, frequency of comorbid conditions, and blood eosinophil count were evaluated. Additionally, questionnaires including A2 and ECRHS scales were used in asthma screening. The diagnostic significance of questionnaires for early detection of late-onset asthma was assessed using ROC analysis. Results and Discussion: The patients examined were comparable in age, sex, and adherence to smoking. Over 63% of the group 1 patients had hereditary history of asthma and sensitization to allergens in contrast to the group 2 patients (0%). Patients in both groups frequently reported choking (group 1: 100%, group 2: 85.1%), cough (100% and 57.4%, respectively), and wheezing (69.7% and 38.3%, respectively). Among comorbidities, the frequency of which was comparable between the groups (p>0.05), arterial hypertension (group 1: 66.7%, group 2: 59.6%) and obesity (60.6% and 42.6%, respectively) were predominant. Over 35% of patients in each group had chronic heart failure. There was a trend toward more frequent development of diabetes mellitus in patients with asthma (30.3% and 12.8%; p=0.054). The sum of A2 and ECRHS scale scores exceeded 4 in all patients with asthma. In group 2, “Probable asthma” was reported by 46.8% of patients in the A2 questionnaire and by 27.7% on the ECRHS scale. According to ROC-analysis, “Probable asthma” in the group 2 patients on A2 scale was recorded at the sum of scores > 6 (100% sensitivity and 82.9% specificity) and > 4 scores (87.8% sensitivity and 87.2% specificity) for ECRHS questionnaire. Conclusions. High diagnostic value of A2 and ECRHS questionnaires was determined in comorbid patients with respiratory symptoms without asthma. In 30% of cases, the questionnaire results established “Probable asthma” in this category of patients.