Seafloor massive sulphide (SMS) deposits have provided critical information on how ancient volcanogenic massive sulphide (VMS) deposits have formed. The original discoveries on mid-ocean ridges, coupled with new research in arc environments has greatly shaped our understanding how seafloor hydrothermal systems in the modern and ancient record formed. The modern environment provides us the ability to understand SMS/VMS in real time and deposits are relatively pristine, whereas ancient VMS deposits are often deformed and metamorphosed, which has obscured many original SMS features and textures, but provide other advantages not available in modern SMS deposits (e.g., 3D geometry of VMS). This presentation will compare key information that can be gleaned from the modern and ancient SMS/VMS environments and how it provides us a comprehensive understanding of seafloor hydrothermal deposit formation. CITATION: Piercey, S, 2019. Comparing and contrasting our knowledge base and gaps in ancient volcanogenic massive sulphide (VMS) deposits via comparisons to modern seafloor massive sulfide (SMS) systems, in Proceedings PACRIM 2019, pp 215217 (The Australasian Institute of Mining and Metallurgy: Melbourne).