Abstract： Objective Periodontitis is an inflammatory disease which may be associated with chronic obstructive pulmonary disease (COPD). Interleukin-19 (IL-19) might be involved in the common inflammatory mechanisms. This study investigated the association of serum levels of IL-19 with periodontitis and COPD in a Chinese population. Methods Fifty-one patients with chronic obstructive pulmonary disease, sixty-one patients with periodontitis, ninety-seven patients with both COPD and periodontitis and twenty-two healthy people were included in the study. The blood serum IL-19 levels was detected by ABC-ELISA. Results The differences in IL-19 expression were significant both between periodontitis group and non-periodontitis group, COPD group and non-COPD group (P ＜ 0.05). However, there was no interaction detected between the two diseases on IL-19 expression. Conclusion Serum IL-19 level increases in both periodontitis patients and COPD patientsand IL-19 might be associated with the pathogenesis of periodontitis and COPD.