Objective To investigate the clinical relevance of TREM-1 and PCT in patients with AECOPD.Methods Forty patients with clinically stable COPD were recruited.According to GOLD lung function classification,the severity of COPD was mild in 5 cases,moderate in 16,severe in 13,and extremely severe in 6.The concentrations of TREM-1 and PCT in the serum were measured in all patients both acute exacerbation and stable stage.Pathogen examinations in the sputum culture were measured in all AECOPD patients.Results The levels of TREM-1and PCT were higher in AECOPD patients (P ＜ 0.05).The levels of TREM-1 and PCT was higher in AECOPD patients in whom sputum bacterial culture was positive than those with negative culture (P ＜ 0.05),but not in sputum viral culture positive patients.Conclusions TREM-1 is a sensitive inflammation marker for AECOPD,and may be use as objective index for AECOPD judgement.The level of TREM-1 was higher in AECOPD patients with bacterial infection while not in AECOPD patients with viral infection.The combined determination of serum TREM-1 and PCT may help to direct application of antibiotic.