M. a total of 44,653 samples tested, 597 (1.3%) showed indeterminate results. Of these, 367 could be analyzed by EIA. Only 15 (15/367, 4.1%) samples were found EIA reactive. Of these, 11 could be tested for HIV-1 RNA. All were HIV-1 RNA negative. In our clinical practice, pregnant women with such indeterminate results are now reassured during posttest counseling that they are very unlikely to be infected with HIV-1. As a consequence, such women with indeterminate results can reliably be considered negative when urgent clinical decisions (such as providing PMTCT prophylaxis) need to be taken. In sub-Saharan Africa, rapid testing for human immunodeficiency virus (HIV) is the most efficient and sometimes the only feasible way to quickly provide information about HIV status among adults and children 18 months of age (6, 29). In contrast to enzyme immunoassays (EIAs) and Western blot assays (WBs), HIV rapid tests are relatively cheap, easy to use, and fast to perform. Most of them do not require refrigeration, sophisticated laboratory equipment, skilled technicians, and an electricity supply. Results from serum, plasma, whole-blood, urine, or saliva samples are obtained by visual reading after a few minutes. Some of the rapid tests can distinguish HIV type 1 (HIV-1) from HIV type 2 (HIV-2). They are also accurate and reliable as a result of applying a quality system maslinic acid approach recommended by the World Health Organization (WHO) (36). Due to their low cost and technical advantages, they have been adopted into national HIV voluntary counseling and testing (VCT) guidelines in many African countries. Their sensitivity and specificity have been studied in Kenya (12), Tanzania (22), Uganda (15), Zambia (30), South Africa (25), KR2_VZVD antibody Cameroon (1), Central African Republic (24), Democratic Republic of Congo (19), Ghana (2), Ivory Coast (32), and Burkina Faso (23, 28). One objective for rapid HIV testing is to minimize the occurrence of indeterminate results (i.e., discordant results when using at least two different rapid tests). It is often quite difficult for HIV counselors and health care providers to disclose such indeterminate results. In the context of interventions for prevention of mother-to-child transmission (PMTCT) of HIV-1 (which can require immediate decisions, notably during labor), medical staff need to know rapidly the HIV status of the woman from the laboratory in order to provide her, or not, antiretroviral (ARV) prophylaxis (5, 26, 27). The prolonged delay in the decision (by performing additional tests or by retesting women 14 days later) can be inappropriate in the clinical routine since women may deliver before obtaining definitive results. The aims of this study conducted among pregnant women from Burkina Faso (West Africa) with a low risk of early HIV-1 seroconversion were (i) to determine the prevalence rates of indeterminate results by using two rapid tests in a sequential algorithm, as recommended in Burkina Faso, and (ii) to assess, using additional tests, the biological significance of indeterminate results in order to define a more rational strategy at the individual and public health levels. (This work was presented in part at the 15th Conference on AIDS and STDs in Africa, Dakar, Senegal, 3 to 7 December 2008 . ) MATERIALS AND METHODS Studied population. The studied population consisted of ARV-na?ve pregnant women from Bobo-Dioulasso (Burkina Faso, West Africa) screened for HIV from January 2005 to December 2007 in order to participate in the multicenter PMTCT Kesho Bora trial (10), which evaluated the impact of highly active maslinic acid antiretroviral therapy (HAART) during pregnancy and breastfeeding on mother-to-child transmission (MTCT). During VCT, HIV screening was performed maslinic acid by two.