A study of gold (Au) mining areas in Tanzania is being undertaken to assess environmental impacts arising from the use of mercury (Hg) in gold extraction. Initial results already indicated the presence of elevated Hg concentrations in environmental samples from the mining areas. The mean Hg concentration in river sediments in 4.19 µg/l. soils within gold mining and processing centres exhibit high Hg content (mean 3.39 µg/g) that decreases rapidly to background regional values within a distance of a few kilometres. A review of published Hg data for sediments, fish and aquatic plants from African inland and coastal waters revealed, with a few exceptions, low Hg concentrations close to natural background levels.