Petrographic, textural and chemical investigations on the Zabargad Island ultramafic association of peridotites and pyroxenite layers allow the main stages of their evolution to be identified. The whole evolution was characterized by three main stages, attributed to different geodynamic situations. These three stages are: 1. (1) early upper mantle evolution and equilibration 2. (2) decompressional upwelling during continental lithosphere rifting 3. (3) late near-seafloor emplacement. The first stage, developed under relatively high P- T conditions, was probably unrelated to the Red Sea evolution and was characterized by deep-seated magmatism. Pyroxenite layers were formed during this stage, consisting of Al-Di and Cr-Di types. According to the major and trace element distributions, the Al-Di pyroxenites can be considered as liquids produced under high-pressure conditions and equilibrated under spinel peridotite fades conditions. Cr-Di pyroxenites approach cumulate compositions produced by solid/liquid fractionation, starting from liquids formed at relatively high pressure. The early lherzolite-pyroxenite association was presumably cooled during its upward movement beneath a continental crust and was completely equilibrated in the spinel facies (at a temperature which was still higher than 1000°C). The second stage was initiated when the continental lithosphere rifting and thinning took place in this region, related to the propagating tensional effects from the southernmost focal upwelling of the Afar Triple Junction. The Zabargad mantle section underwent progressive, almost adiabatic, decompression during upwelling. At that time, H 2O-rich fluids produced equilibrium crystallization of pargasitic amphiboles under sp-lherzolite facies conditions. The solidus temperatures of the Zabargad lherzolites were lowered, causing a sporadic incipient partial melting at relatively low pressure, with the production of depleted lherzolite residua and basaltic melts, crystallized “in situ” as gabbroic material. Utilizing the available REE data and the results of the modelling of a non-modal equilibrium partial melting process on a sp-lherzolite composition, it is evident that the more depleted Zabargad lherzolites closely approach compositions of refractory residua after low-degree (about 10%) partial melting at relatively low pressure on a model mantle source very similar to the less depleted Zabargad lherzolites. This stage was accompanied by plastic deformation, the main direction of which was about north-northwest, almost parallel to the future Red Sea axis. The progressive, relatively rapid, decompression produced incomplete equilibration under low-pressure conditions (pl-bearing assemblages). The third stage of near-seafloor emplacement was accompanied by increasing interaction with H 2O-rich metasomatic fluids, which gave rise to widespread amphibolitization of the ultramafic and gabbroic rocks and, later on, to typical metasomatic mineralization (phlogopite, apatite, scapolite and sodic plagioclase). This final stage in the evolution was facilitated by the development of almost vertical shear zones which were variably oriented, broadly parallel both to the Red Sea axis and to the main transform faults detected in the area. Important fluid/rock interaction along fractures and metasomatic mineralization (serpentine minerals, gem-quality olivine, scapolite and cancrinite) characterize the last step of this third stage, preceding the shallow basalt dyke intrusion and the final tectonic emplacement on the seafloor.