This text focuses on the biological interactions of sulphur compounds which arise specifically from the presence of the sulphur atom within the molecule. The book opens with introductory chapters on the chemistry and biology of sulphur, before tackling the field by introducing compounds which share a common chemical combination. In general, following a description of the uses and impact upon the biological field, specific chemical group characteristics are discussed together with the biological activity and structure-activity relationships where known. The toxicity of such compounds, their consequences in biochemical and clinical terms, and their mechanisms of biological interaction are then addressed.