Neoproterozoic petroleum systems occur in several parts of the world, based on organic-rich hydrocarbon source rocks deposited during the late Neoproterozoic high sea level. The Dalradian Supergroup in Argyll, Scotland, shows evidence for coupled source rock and reservoir rock. The Easdale Slate contains organic carbon, rich enough to be a good source rock. Pore spaces of the Scarba Conglomerate are filled with oil residue. Pyrite spatially associated with the oil residue may reflect microbial sulphate reduction. Despite greenschist-facies metamorphism, the Easdale Subgroup records a hitherto unrecognized petroleum system, which adds to a global picture of late Neoproterozoic hydrocarbon generation.