In this retrospective study, complete Brucella serology data from the annual national brucellosis testing program and disease investigation for the years 2008-2010 was collated and analyzed to estimate the prevalence of brucellosis in sheep in the Karas Region of Namibia. A total of 22,994 serological results from 762 flocks screened using the Rose Bengal test (RBT) and confirmed using the complement fixation test (CFT) were analyzed. An overall prevalence of 0.14% was recorded over the 3 years. Yearly prevalence was 0.19% (2008), 0.05% (2009), and 0.18% (2010). At district level, brucellosis prevalence was estimated to be between 0 and 0.49%. On positive farms (n = 32), prevalence was between 2.25 and 30%. True prevalence was zero at district level and in all the three study years. We concluded that the prevalence of Brucella antibodies in sheep was low taking into account that some farmers may have vaccinated against the disease. The low prevalence confirms the effectiveness of existing brucellosis control measures implemented by the official veterinary services.