To satisfy the increasing demand by the rapidly growing German industry for environmentally responsible hazardous waste disposal solutions, chemotoxic waste has been, since 1972, geologically isolated in disused portions of underground mines located in geologically stable salt formations beneath impermeable overburden strata. Requirements for permanent safe isolation of hazardous waste, anchored in the concept of multiple barriers, have been incorporated into German and European regulations and applied in three operating underground repositories thus far. On the basis of the same safety concept and a preference for waste avoidance and reuse rather than disposal, the reuse of suitable waste as mine backfill has also increased. Excellent long-term experience with hazardous waste disposal and reuse in German salt and potash mines encourages the practice of deep geologic isolation of chemotoxic waste worldwide.