The Hillside Cu-Au deposit (Conor et al., 2010; Ismail et al., 2014) is located along the eastern coast of the Yorke Peninsula, South Australia (Fig. 1). Mineralization is hosted by a highly-deformed sequence of metasedimentary rocks belonging to the Moonta-Wallaroo Group, Mesoproterozoic and Hiltaba Suite granites, and gabbros. The deposit and associated alteration display strong affinities with the ~1.59 Ga mineralization event responsible for Olympic Dam, and a number of smaller IOCG (iron-oxide-copper-gold) deposits and prospects across the Olympic Cu-Au Province but features a distinct, skarn envelope. The skarn is patchy and tied to immediate contacts between igneous rocks and a carbonate protolith indicating a deep skarn setting. The mineralized skarn occurs along four distinct faults, part of a major structure in the area the Pine Point Fault. Mineralogical-petrographic work at Hillside (Ismail et al., 2014) identified a transition from an early magmatic to skarn stage (pyroxene-albite) to main calcic skarn formation and to a late-hydrothermal stage (ore stage). The study also showed the high degree of skarn retrogression from prograde garnet ± pyroxene+ magnetite to clinozoisite ± actinolite + hematite assemblages. Main ore (chalcopyrite) deposition is associated with formation of late-stage quartz-calcite ± chlorite (interstitial and as veins). Each stage is reflected by evolving REE fractionation trends in the main calc-silicates and accessory minerals, notably titanite and apatite. The thermal evolution of the Hillside deposit from an initial ~700 °C early skarn down to a retrograde skarn-ore stage at ~500 °C is shown by application of Zr-in-titanite geothermometry (Ismail et al., 2014, using the calibration of Hayden et al., 2008). In an attempt to further constrain the thermal evolution and salinities of skarn and ore-forming fluid(s) at Hillside, we have carried a reconnaissance fluid inclusion study, targeting inclusions in minerals typifying these stages. The sample suite for this study includes all key rock types from across the deposit at Hillside: mineralized skarn (garnetite and pyroxene-garnet skarn); skarn-spotted marble; albitized gabbro; granite and pegmatite. 34 doublepolished thin sections were prepared and inclusion populations identified and located using a Nikon optical microscope (Adelaide Microscopy, University of Adelaide). Microthermometry was carried out on a Linkam THMSG-600 heating-cooling stage, allowing for phase transition temperatures measurements between -196 °C and 600 °C, at the State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Guiyang. Laser Raman Spectroscopic analysis was carried out at the same laboratory to confirm the identity of phases present in inclusions. Roniza ISMAIL, LIN Ye, Cristiana L. CIOBANU and Nigel J. COOK, 2014. The Hillside Cu-Au Deposit, South Australia: A Preliminary Fluid Inclusion Study. Acta Geologica Sinica (English Edition), 88(supp. 2): 1454-1456.