Because it is a strong oxidant that does not form trihalomethanes, chlorine dioxide is becoming a popular alternative to chlorine for disinfecting domestic water supplies. However, when water disinfected with chlorine dioxide is used in hemodialysis therapy, care must be taken to ensure removal of all oxidants that could adversely affect the patient. This case study examines the efficiency of water treatment processes typically used at dialysis centers for removing chlorine dioxide, chlorine, and their residual oxidants. Initial data showed that chlorite ion and free chlorine were effectively removed, but because chlorine dioxide and chlorate ion could not be conclusively identified in the water supply to the clinic or in the final product water of the treatment train, their removal could not be determined. Includes 21 references, tables, figure.