Chlamydia Pneumoniae "CP" is a common pathogen that has been linked to coronary artery disease . Also , CP antigen has been demon­strated in valve biopsy specimens from patients with acquired aortic valve stenosis & in patients with cul­ture negative endocarditis . The aim of this paper is to study the presence of CP in both aortic & mitral valves by using polymerase chain reaction "PCR" & its relation to the pathology of the valve . 27 patients "16 males" who underwent aortic & mitral valve replacement were studied . Key dem­ographic & clinical data were collect­ed including age , gender, past histo­ry of rheumatic fever , NYHA class , preoperative 12 leads ECG , Chest X-
ray & Echocardiography . One portion of the valve leaflet was sent for patho­logic examination to detect the nature of valve disease e.g. rheumatic or non-rheumatic & the other portion was sent for PCR study . The age ranged from 19 to 55 years with mean valve 36.48 ± 11.46 . 5 patients had isolated aortic valve stenosis , 12 had mitral valve disease & 10 had double valve disease . Aschoff body & cells were seem in 11 patients and 5 pa­tients had non-rheumatic degenera­tive aortic stenosis . 7 out of 27 cases (25.9%) were PCR positive , 5 of them were isolated non-rheumatic aortic stenosis and represent (33.3%) of aortic cases . The remaining 2 PCR positive cases were rheumatic mitral valve disease one of them was se-