Abstract : Two major types of Cu-Au ore deposits, genetically related to the Upper Cretaceous volcanic arc magmatic activity are recognised in the Panagyurishte district, Sredna Gora zone (Bulgaria): replacement type epithermal and porphyry copper deposits. Detailed studies of mineral composition, trace-element distribution, stable (O, H, S) and radiogenic (Sr, Pb) isotopes and fluid inclusions (visible and IR light) have been performed in the Radka and Elshitsa epithermal and the Vlaikov Vrah porphyry-Cu deposits, in order to constrain the origin of epithermal mineralisations and to test the hypothesis of the genetic connection between porphyry and epithermal systems. The results of field work and laboratory analyses confirmed the epigenetic character of studied mineralisations and permitted us to characterise them as deeper parts of high- to intermediate-sulphidation epithermal systems. The deposits were formed by oxidised, relatively acidic fluids with fluctuating , but generally high, sulphur fugacity. Four principal ore stages can be recognised in the epithermal deposits: an early stage of massive As-bearing pyrite, a copper stage with a very characteristic signature (Bi-Te-Se-As-Sn-Pb), a polymetallic (Zn-Pb-Cu) stage, and a late anhydrite stage indicating the progressive oxidation of the system. Fluid inclusion and stable isotope study reveal the participation of magmatic fluids to the ore formation, and their mixing with meteoric water during the late stages of evolution of the hydrothermal system. Radiogenic isotope study indicates extensive fluid circulation through the metamorphic basement and shows that both the porphyry-Cu and epithermal Cu-Au deposits in the southern part of the Panagyurishte district formed during the same metallogenic event. Upper Cretaceous intrusive rocks are the most probable source of metals for the formation of economic mineralisations.