Introduction The EXA cerbations of C hronic obstructive lung disease (COPD) and their O utcome S (EXACOS) International Study aimed to quantify the rate of severe exacerbations and examine healthcare resource utilisation (HCRU) and clinical outcomes in patients with COPD from low-income and middle-income countries. Methods EXACOS International was an observational, cross-sectional study with retrospective data collection from medical records for a period of up to 5 years. Data were collected from 12 countries: Argentina, Brazil, Chile, Colombia, Costa Rica, Dominican Republic, Guatemala, Hong Kong, Mexico, Panama, Russia and Taiwan. The study population comprised patients ≥40 years of age with COPD. Outcomes/variables included the prevalence of severe exacerbations, the annual rate of severe exacerbations and time between severe exacerbations; change in lung function over time (measured by the forced expiratory volume in 1 s (FEV 1 )); peripheral blood eosinophil counts (BECs) and the prevalence of comorbidities; treatment patterns; and HCRU. Results In total, 1702 patients were included in the study. The study population had a mean age of 69.7 years, with 69.4% males, and a mean body mass index of 26.4 kg/m 2 . The mean annual prevalence of severe exacerbations was 20.1%, and 48.4% of patients experienced ≥1 severe exacerbation during the 5-year study period. As the number of severe exacerbations increased, the interval between successive exacerbations decreased. A statistically significant decrease in mean (SD) FEV 1 from baseline to post-baseline was observed in patients with ≥1 severe exacerbation (1.23 (0.51) to 1.13 (0.52) L; p=0.0000). Mean BEC was 0.198 x10 9 cells/L, with 64.7% of patients having a BEC ≥0.1 x10 9 cells/L and 21.3% having a BEC ≥0.3 x10 9 cells/L. The most common comorbidity was hypertension (58.3%). An increasing number of severe exacerbations per year was associated with greater HCRU. Discussion The findings presented here indicate that effective treatment strategies to prevent severe exacerbations in patients with COPD remain a significant unmet need in low-income and middle-income countries.