Introduction:Stenotrophomonas maltophilia is an emerging Gram-negative MDR bacteria. In patients with chronic obstructive pulmonary disease (COPD), it is mostly found in those with severe exacerbation of COPD requiring mechanical ventilation. The significance of S. maltophilia when detected in the sputum of ambulatory patients with COPD is uncertain. Objective: To access the prevalence and the risk factors of the presence of S. maltophilia in the sputum of ambulatory patients with COPD and to determine whether it was associated with prognosis. Methods: All consecutive unselected ambulatory patients with GOLD 2-4 COPD were recruited between January 2017 and September 2019 from the COPD clinic of a tertiary care hospital. Presence of S. maltophilia was defined by a positive sputum culture for S. maltophilia. Demographics, COPD characteristics, comorbidities and known predisposing risk factors associated with S. maltophilia were collected from medical records. Results: S. maltophilia was detected in the sputum of 41/393 (10%) of study participants. Comorbidities, exacerbation, use of oral steroids and carbapenems in the previous year were risk factors for the presence of S. maltophilia. After adjusting on confounding factors associated with mortality including age, Charlson comorbidity index and FEV 1 , S. maltophilia was significantly associated with mortality (adjusted hazard ratio 2.3; 95% CI 1.1-4.9). Conclusion:In the current study, we found that 10% of ambulatory patients with GOLD 2-4 COPD had S. maltophilia detected in their sputum. In addition, S. maltophilia may represent a marker of overall morbidity in patients with COPD.