This paper presents a review of petrological-geochemical studies at the Yoko-Dovyren Massif with an emphasis on relations between parameters of the parental magma, a model for the genesis of the lower con- tact zone, and the nature of Ni sulfide ore mineralization, including the evaluation of the possible ore potential. Arguments are presented in support of the conclusion that the Dovyren magma brought much intratelluric oli- vine of the composition Fo 85-87 into the chamber, and the composition of the initial melt corresponded to gab- bronorite or moderately magnesian basite with no more than 10 wt % MgO. The probable temperature of the parental magma was approximately 1200-1250°e , and the sulfur solubility did not exceed 0.10-0.12 wt % ( P = 1 kbar, WM buffer). The comparison of this estimate with the average S contents in the bottom plagioperi- dotites ( 0.12 ± 0.06 wt %) indicates that the initial magma was saturated with a sulfide phase. For the first time the problem of the composition of contaminated dunites was formulated (these rocks occur in the Layered Series and contain more magnesian olivine Fo 87-92 ). The reason for the increase in the mg# of olivine is thought to be the partial melting and compaction of the original cumulates due to the infiltration of intercumulus melt enriched in volatile components. The volatiles were presumably provided by the thermal decomposition of car- bonate xenoliths, a process that resulted in an increase in the CO 2 pressure and the transfer of calcite-magnesite components of carbonates into the melt. This follows from (1) the occurrence of magnesian skarn developing after carbonates, (2) high CaO contents in olivine form the contaminated dunite, (3) the appearance of olivine- bearing pyroxenites and wehrlites in the upper part of the dunite zone, (4) correlation between the olivine and chromite composition in the contaminated and uncontaminated dunites, (5) broad variations in the oxygen iso- topic composition of olivine and plagioclase from rocks of the Layered Series, (6) experimental data on the dis- solution of carbonates in alkali basalt melts, and (7) analogies with isotopic-geochemical characteristics of rocks from the Jinchuan ultramafic complex. Petrological implications of the interpretation of the Dovyren chamber are discussed with reference to closed and flow-through (during an initial stage) magmatic systems. A petrological-geological model is proposed for the genesis of the Synnyr-Dovyren volcanic-plutonic complex and related Ni sulfide ore mineralization. The potential resources of Cu-Ni sulfide ores in the plagioperidotites are evaluated with regard to the still-unexposed part of the massif.