The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recent studies have emphasized the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are be- lieved to have formed from fluids of magmatic or metamorphic origin and exhibit characteri stic 6180 values. These values also give information regarding temperatures and the degree of equilibrium. Preliminary oxygen data for some important gold deposits of eastern Australia are evaluated in the con- text of styles of mineralization.