Sixty-four public water supply systems in South Dakota were fluoridating in September 1973, serving an estimated population of 327,000. Twenty-seven communities, population 15,000 were using water sources containing natural fluorides within the recommended range. Of the 276 reported public water supplies in the state, 91 (33 percent) were fluoridating or using one or more water sources containing natural fluorides within the recommended range. Recommendations are offered regarding: promotion of fluoridation of all public water supplies in the state; maintaining fluoride ion content within recommended limits; enforcement of state fluoride standards; requirements for fluoride ion analyses; development of specific regulations for the installation of fluoridation equipment; promulgation of regulations for storage and handling fluoride chemical compounds and of training in safe handling practices.