Relevance of studying epithermal Au-Ag deposits in northeastern Russia lies in both fundamental scientific and applied economic significance. With the depletion of rich conventional primary and placer gold deposits, interest in previously underestimated epithermal-type deposits in remote regions of the Far East and Kamchatka has sharply increased. Despite low metal grades and complex logistical conditions, these deposits currently form a significant reserve for Russian gold mineral resource base, requiring comprehensive study. This research aims to determine the mineral form of gold occurrence, its paragenetic associations, indicator minerals, possible transport and deposition mechanisms, and geochemical parameters of the ore-forming system (such as temperature, sulfur fugacity, and pH). Aim. To reconstruct the ore-forming conditions of the Levoberezhnoe epithermal deposit through integrated analysis of mineral associations, temperature regime, and fluid parameters. Methods. Microthermometry, mineralogical geothermometry, SEM-EDS, XRF, XRD analysis, and X-ray microtomography. Results and conclusions: The comprehensive study revealed progressive cooling of the Levoberezhnoe ore-forming system from 380 to <200°C, confirmed by microthermometry and mineralogical geothermometry data. Sulfur fugacity calculations (logαS₂= –7...–16,5) show that pyrite crystallized initially during system evolution, while subsequent changes (interaction with meteoric waters, cooling) led to fluid neutralization and reduction, causing marcasite crystallization and electrum deposition under decreasing sulfur activity. The identification of a late mineralization stage (logαS₂ ≈–16,5 at T<200°C), marked by Se-bearing acanthite, indicates fluid regime evolution toward lower sulfur activity, increased acidity (pH), and greater arsenic and antimony involvement. Gold precipitation in association with arsenian pyrite and arsenopyrite is facilitated by FeAsS dissolution, which produces localized redox gradients favoring Au reduction. These results significantly enhance current understanding of gold-silver mineralization genesis in epithermal systems and can be used to develop exploration criteria for similar deposits.