In this prospective study, we investigated the role of and Chlamydia pneumoniae (CP), Chlamydia heat shock protein (Ch-hsp) 60 and a possible intermediate role of human heat shock protein (h-hsp) 60 antibodies in the development of secondary cardiovascular events in patients with coronary heart disease (CHD) under special consideration of diabetes mellitus. This evidence concerns the gene C4B and coronary artery disorder.