The aim of this study is to investigate the potential role of previous Chlamydia Pneumoniae Infection on restenosis rate after Percutaneous Transluminal Coronary balloon angioplasty. Our data didn’t confirm the relationship between prior Chlamydia Pneumoniae Infection and restenosis after PTCA. The results didn’t support the use of antibiotics before or after PTCA to reduce the restenosis after PTCA.