To determine factors associated with HIV status unawareness and assess HIV prevention knowledge and condom use among people living with HIV/AIDS (PLHIV) in Mozambique. Cross-sectional household-based nationally representative AIDS Indicator Survey. Analyses focused on HIV-infected adults and were weighted for the complex sampling design. We identified PLHIV who had never been tested for HIV or received their test results prior to this survey. Logistic regression was used to assess factors associated with HIV status unawareness. Of persons with positive HIV test results (N = 1182), 61% (95% confidence interval CI 57-65%) were unaware of their serostatus. Men had twice the odds of being unaware of their serostatus compared with women adjusted odds ratio (aOR) 2.05, CI 1.40-2.98. PLHIV in the poorest wealth quintile were most likely to be unaware of their serostatus (aOR 3.15, CI 1.09-9.12) compared to those in the middle wealth quintile. Most PLHIV (83%, CI 79-87%) reported not using a condom during their last sexual intercourse, and PLHIV who reported not using a condom during their last sexual intercourse were more likely to be unaware of their serostatus (aOR 2.32, CI 1.57-3.43) than those who used a condom. Knowledge of HIV-positive status is associated with more frequent condom use in Mozambique. However, most HIV-infected persons are unaware of their serostatus, with men and persons in the poorest wealth quintile being more likely to be unaware. These findings support calls for expanded HIV testing, especially among groups less likely to be aware of their HIV status and key populations at higher risk for infection.