The implementation of HIV counseling and testing services for HIV surveillance in Africa is discussed. The antiretroviral treatment for HIV-infected adults has expanded with the help of WHO's '3 by 5' strategy. In Tanzania, the expansion aimed to have more than 600 voluntary HIV counseling and testing sites by the year 2006. Data-collection activities in voluntary HIV counseling and testing clinics have been expected to fulfil donor-driven reporting requirements that include program monitoring and assessment. Aggregation of data from various counseling and testing services to obtain national estimates presents analytical problems as patients referred from medical wards to a testing center within a hospital are different from those using a walk-in center located in the community. Routine data-collection activities in voluntary HIV counseling and testing centers serve various purposes to ensure proper test results.