Au-Ag deposit with a total known endowment of >10 M oz Au and ~Ag 80 M oz Ag. Mining on the system has occurred during 100 of the last 126 years. Martha is a very large and complex vein system, with multiple phases of over-printing mineralisation.From 1882 to 1952, the Martha system was mined continuously underground, reaching a depth of 600 m below surface with some 175 km of underground tunnels on 15 levels. In this time, a total of 5.6 Moz of Au and 38.4 Moz of Ag was produced.The mine re-opened in 1988 and has been mined continuously since. The Martha open pit mined the top of the main Martha system from 1988 until 2015, reaching a depth of 230 m (Figure 1). Modern underground mining commenced at Favona in 2004, Trio in 2010, and Correnso in 2014, where it continues today. CITATION: Stewart, M, Crawford-Flett, L and Church, P, 2019. Multi-scale modelling of the Martha epithermal Au-Ag deposit, Waihi, New Zealand, in Proceedings PACRIM 2019, pp 121125 (The Australasian Institute of Mining and Metallurgy: Melbourne).