Native sulphur has had limited success as a medicinal agent. There is, however, hardly a class of drugs which does not contain compounds having sulphur in their structure. Sulphur-containing dyes have given rise to many clinically useful substances, others, such as the -lactam antibiotics, have been developed from naturally occurring molecules and yet others have been designed on the basis of a detailed understanding of physiological mechanisms. Sulphur occurs in drug molecules in all its oxidative states and in all its forms of organic combination. Organo-sulphur compounds, unquestionably form a major therapeutic resource and their potential remains to be further exploited.