High uptake of HIV voluntary counseling and testing (VCT) services is important for the success of HIV workplace programs in sub-Saharan Africa. From 2001 onwards, Heineken, a multinational brewing company, implemented a comprehensive HIV prevention and treatment program for employees and their dependents of its African subsidiaries. Confidential in-house VCT is part of this program. VCT uptake dynamics over time, and factors associated with early uptake were studied. Between September 2001 and December 2007, 9723 adult beneficiaries were tested for HIV in 14 company sites in five African countries. Three hundred and seventy (3.8%) of tested persons were infected with HIV-1. During the first 12 months 1412 tests were done, compared to 8311 tests in the subsequent years. The annual average uptake of testing among eligible persons varied between 15 and 32%. The coverage was higher among female compared to male employees, and higher among female compared to male spouses. Distinct peaks in uptake were linked to specific local events. HIV-1 infected persons were significantly more likely to be tested in the early period. The proportion of HIV-1 infected persons among testees was 8.8% in the first 12 months compared to 3.0% in the subsequent period (p<0.001). HIV-1 infected persons diagnosed in the early period were in a more advanced clinical stage, and had a significantly lower CD4 count than those tested later (median CD4 count 227 vs. 314 cells/microl; p=0.002). In this workplace program, HIV-1 infected individuals came earlier for an HIV test than uninfected people, and people with advanced infection came earlier than those with less advanced disease. Employees' spouses are harder to reach than employees and extra efforts should be undertaken to reach them as well. Uptake of HIV testing can be actively influenced by educational or promotional activities.