Abstract： Objective To analyze the sensitivity and specificity of polymerase chain reaction (PCR) tests in the detection of cytomegalovirus (CMV) in the diagnosis of patients with acquired immune deficiency syndrome (AIDS), using aqueous humor samples.Methods 25 AIDS patients (including 21 men and 4 women) were studied.The age of the patients varied from 24 to 59 years, with an average of (39.2 ± 9.3) years.The CD4+ T cell count was from 1 to 523 cells/tμl, with a medium of 40 cells/μl.They were infected with human immunodeficiency virus(HIV)for a period from 15 days to 9 years with a median of 10 months.They were divided into three groups according to the fundus and treatment, including untreated cytomegalovirus retinitis (CMVR), treated CMVR and control group.There were 10 patients without anti CMV treatment and 7 patients treated previously with foscarnet or ganciclovir whose eyes were diagnosed CMVR.Control group has 8 patients who had normal fundus or minor retinopathy excluded from CMVR.Approximately 100 μl of aqueous humor was obtained by anterior-chamber paracentesis and PCR was performed in all cases.Results There were CMV DNA in 9 of 10 eyes with untreated CMVR (90.0％sensitivity).Of 7 specimens from eyes with treated CMVR, 3 were CMV PCR positive (42.9％ sensitivity).All 8 samples of the control group were negative for CMV DNA, indicating the clinical specificity of our PCR was greater than 99.9％ for CMVR.The anterior chamber paracentesis did not cause any complications in our patients except for a patient with subconjunctival hemorrhage.Conclusions The assay had an estimated sensitivity of 90.0％ in detecting untreated CMVR and a sensitivity of 42.9％ in detecting CMVR that had been treated.The specificity of this assay was greater than 99.9 ％.