The study presents textural and mineral chemistry data, as well as whole-rock and mineral separate Os-isotopic compositions for PGM assemblages from deep portions of the oceanic mantle. The extensive data set of Os-isotope compositions of intimately intergrown grains of Os-rich alloy and Ru-Os sulfide from ophiolite-type massifs of different ages is firstly evaluated. The Os-isotope results identify a restricted range of 'unradiogenic' 187Os/188Os values for coexisting laurite and Os-rich alloy pairs that form 'primary' PGM assemblages at Hochgrossen, Shetland, and Verkh-Neivinsk. Similarly 'unradiogenic' 187Os/188Os values have been identified in the chromitite and mineral separates from 'primary' and 'secondary' PGM assemblages, implying that the whole-rock Os-isotope budget is largely controlled by the laurite-alloy pair.