The Riagan porphyry copper system is located in Bam, Southeastern Iran (Kerman Provice),and is associated with diorite/granodiorite to quartz-monzonite of Miocene age that intruded Eocene volcano- sedimentary rocks. Copper mineralization was accompanied by mainly phyllic and less potassic alteration. Field observations and petrographic studies demonstrate that emplacement of the Raigan stock took place in several intrusive pulses, each with associated hydrothermal activity. Molybdenum is reported in any stage of hydrothermal evolution through the system. Due to lack of information, the petrogenesis interpretation is mainly based on the field observation. It seems that early hydrothermal alteration produced a potassic assemblage (orthoclase-biotite) in the central part of the stock, propylitic alteration occurred contemporaneously with potassic alteration, but in the peripheral parts of the stock, and phyllic alteration formed later, overprinting all the earlier alteration (the most majority alteration in Raigan system). The early hydrothermal fluids are represented by high temperature (487 °C to 598 °C), high salinity (up to 61.1 wt % NaCI equiv.) liquid-rich fluid inclusions, and high temperature (397 °C, 401 °C), low-salinity, vapor-rich inclusions. These fluids are interpreted to represent an orthomagmatic fluid which boiled episodically; the brines are interpreted to have caused potassic alteration, containing generation of chalcopyrite. Propylitic alteration is attributed to a liquid-rich, lower temperature (523 °C to 298 °C), Ca-rich, evolved meteoric fluid. Influx of meteoric water into the system, and mixing with magmatic fluid produced deep albitization, and shallow phyllic alteration. This influx also caused dissolution of early formed copper sulfides and remobilization of Cu into the sericitic zone where it was resystemed in response to a boiling-induced decrease in temperature. Supergene alteration was minor and restricted to a thin blanket of Cu-sulfides.