The HIV-AIDS virus has spread rapidly over the last two decades, with countries in the Sub-Saharan region of Africa accounting for nearly 72% of the global AIDS deaths. A key issue facing policy makers is the long gestation period between the time that the HIV positive status of an individual becomes full-blown AIDS. During this period most individuals show no outward sign of their HIV infection. Being knowledgeable of their HIV status is therefore vital to contain and prevent further infections. However, nearly 95% of all Africans are unaware of their HIV status. In this paper, we use the 2003 Ghanaian Demographic Health Survey (GDHS) dataset, to estimate the likelihood of voluntary testing for AIDS. Our estimation strategy estimates a series of models that take into account the joint determination of AIDS-related knowledge and the likelihood of being tested. Our analysis finds that individuals with greater knowledge of ways to avoid AIDS were significantly more likely to be aware of the transmission mechanisms of AIDS, belong to the highest wealth quintile and were better educated. However, contingent on knowledge these individuals were significantly less likely to get tested.