Backfilling is the process whereby waste material (generally metallurgical tailings or prepared aggregate) is placed back underground into open mine workings (stopes). Backfill is typically used for the following applications: as a working platform, an artificial roof, a stope/void filler, an artificial sidewall, a pillar replacement and to limit surface subsidence and adverse damage to water. The most common methods are as a slurry or as a paste. Slurry filling has many transport advantages but has poor post filling performance. Paste filling has high transportation pressures so often needs pumps but has generally good performance once placed. Foamed backfills however have the potential to offer transport advantages and good post placement performance. The main advantage of using foam in backfill is to transport the backfill with low pressure losses then defoam the backfill so it is effectively placed with even less water than in a paste. If the placed backfill does not defoam under its own weight, then a defoaming agent (e.g. diesel) should be added otherwise the placed density is low and this adversely affects the backfill performance (especially if it is also cemented). This paper discusses the potential and gives some examples where foams have been used for underground filling applications.