Thirty-one patients with middle ear effusion were evaluated for the presence of chlamydia pneumonia by using polymerase chain reaction (PCR) assay. The presence of chlamydia neumonia was 19. 3% (6/31). The results indicated that PCR assay is a highly sensitive and specific for the detection of chlamydia pneumonia in the middle ear effusion and chlamydia pneumonia may be an aetiological agent of middle ear effusion.