Recent advances in comminution and heap leach technology have resulted in the development of many large-scale, low-grade open pit mines that coincide with areas of historical underground workings. Twoand three-dimensional numerical modelling has been conducted to assess the interaction between open pit slope stability and remnant underground voids. Most design analyses for open pit slopes assume a two-dimensional problem geometry. This is not the condition encountered in practice - particularly when remnant underground voids interact with a large-scale open pit slope. Three-dimensional numerical models have been shown to provide a more realistic representation of the interaction between overall open pit slope stability and remnant underground voids.