Objective: Current evidence on the immunogenicity of influenza vaccination in patients with chronic obstructive pulmonary disease (COPD) is limited. To address this need for additional knowledge, we conducted a study on the immunogenicity of trivalent seasonal influenza vaccine (TIV) in COPD patients.Methods: We recruited patients from respiratory outpatient clinics of three hospitals in Tangshan, Hebei province who had stable confirmed COPD, were less than 80 y old, and reported not having had influenza or receiving TIV during the study season prior to enrollment. Patients who had a history of allergy to any TIV component or were classified as having very severe COPD were excluded from the study. Eligible and consenting participants were given one dose of TIV after obtaining a baseline blood sample. A second blood sample was obtained 5 weeks later. We used hemagglutination inhibition (HI) assays to measure antibody responses. We considered seropositive to be an HI titer ≥1:10. We considered seroprotection to be an HI titer ≥1:40 and seroconversion to be either a change from seronegative to a post-vaccination titer of ≥1:40 or a fourfold rise in antibody titer among baseline seropositive subjects. Each subject was followed for 1 month to assess the frequency and type of adverse events.Results: Eighty-eight subjects completed our study; the median age was 64 y; most (62.5%) had moderately severe COPD; 48.9% of the subjects had comorbid conditions in addition to COPD. Post-vaccination seropositive rates for influenza H1N1, H3N2, and B were all 100%; corresponding seroprotection rates were 96.6%, 93.2%, and 98.9%; seroconversion rates were 81.8%, 87.5%, and 75.0%. There were no statistical differences in seroconversion (P = .10) and seroprotection (P = .30) among the three types of influenza virus. Geometric mean titers (1:) of HI antibodies to H1N1, H3N2, and B were 18.8 (95% CI: 14.0-25.1), 12.2 (95% CI: 9.6-15.4), and 31.8 (95% CI: 26.1-38.8) at baseline, and 267.0 (95% CI: 213.8-333.4), 190.3 (95% CI: 151.7-238.6), and 201.1 (95% CI: 166.5-242.8) after vaccination.Conclusion: The immunogenicity of one dose of influenza vaccine was excellent in COPD patients. Our study supports recommending influenza vaccination for COPD patients to provide protection from influenza and its complications.