We describe the results of a study to determine the prevalence and characteristics of cytomegalovirus (CMV) retinitis among HIV-infected patients in Vietnam. We conducted a cross-sectional prospective study of patients with CD4 lymphocyte count ≤100 cells/mm(3)recruited from public HIV clinics. The diagnosis was made by a trained ophthalmologist using slit lamp biomicroscopy and corroborated on fundus photography. A total of 201 patients were screened. The median age was 32 years, 77% were men, median CD4 count was 47 cells/mm(3), and 62% were on antiretroviral treatment. Prevalence of CMV retinitis was 7% (14/201, 95% CI 4-11%). CMV retinitis was not associated with age, gender, injection drug use, CD4 count, WHO clinical stage, or antiretroviral treatment status. Blurring of vision and reduced visual acuity <20/40 were associated with CMV retinitis, but only 29% of patients with the diagnosis reported blurry vision and only 64% had abnormal vision. On multivariate analysis, the sole predictor for CMV retinitis was decreased visual acuity (OR 22.8,p < 0.001). In Ho Chi Minh City, CMV retinitis was found in 7% of HIV-infected patients with low CD4. HIV-infected patients with a CD4 count <100/mm(3)or who develop blurring of vision in Vietnam should be screened for CMV retinitis.