This study explored the effects of Chlamydia pneumoniae (Cpn) infection in elderly patients with Coronary Heart Disease (CHD), as well as related treatment strategies. Serum levels of Endothelin-1 (ET-1), Interleukin-6 (IL-6), C-reactive protein, fibrinogen, soluble vascular cell adhesion molecule-1, and cardiac troponin-1 were determined in 81 elderly CHD patients with Cpn infection (group A) and 82 elderly CHD patients without Cpn infection (group B). Patients in group A were treated with oral azithromycin; serum Cpn-immunoglobulin (Ig) M and (Ig) G levels in group A were measured before and after treatment. Levels of various indicators in group A were higher than those in group B (P<0.05), while the titres of Cpn-IgA and Cpn-IgG in group A were lower than those in group B (P<0.05). Cpn infection may result in increases in inflammatory factors. Azithromycin treatment may reduce the antibody titer, which may reduce the incidence of adverse events in elderly patients with coronary heart disease.