A worked-out area of the operating Helibronn rock-salt mine is being used as a repository for fly-ash waste from incineration plants. The waste is packed in large bags, handled by fork-lifts, trucks, and cranes, and stacked 11-m-high. In addition insolubles from the re-saturation of brine for electrolysis using rock salt are stowed in bulk. Special care is taken to isolate waste-disposal activities from the salt mining and hoisting operations. Considerable interest is being shown in the underground disposal of waste in Germany, particularly as existing landfill sites are approaching the end of their lives and the establishment of new sites is meeting strong opposition from local populations. The problems encountered in the disposal of fly ash in salt mines are discussed.