Although tungsten is an important material in some industrial and chemical processes, the biological and biochemical effects, including the toxicity, of this compound are not known well. This article reviews recent advances in this area and discusses several unique properties of polyoxotungstates. The toxicity of sodium tungstate is relatively low compared with that of other heavy metal compounds such as mercury chloride. However, polyoxotungstates such as tungstophosphate may have several unique effects on specific biological systems. Evidence suggests that this might be due to a charge interaction.