The site of Renaghju has the largest excavated area of any Neolithic site on the island of Corsica (Western Mediterranean). Its lowest layer, exposed over a few hundred meters square contained a rich Early Neolithic Cardial ceramic and lithic industry dated by 14C to the second half of the 6th millennium BC. Obsidian, a raw material exogenous to the island, comprises ca. 15 % of the chipped stone industry. The provenance of 622 obsidian artefacts (84 % of the total assemblage) was determined through a combination of visual characterization, together with noninvasive particle-induced X-ray emission spectroscopy (PIXE) and energy dispersion spectrometer of a scanning electron microscope (SEM-EDS) on millimeter-sized polished fragments. This is, by far, the largest sample of obsidian artefacts analyzed from a Corsican Neolithic site. All but one of the artefacts was found to be made of obsidian from sources associated with the volcanic complex of Monte Arci on the nearby island of Sardinia. Obsidian from each of the three major Monte Arci sources exploited during the Neolithic were identified, with a predominance of obsidians of the SA and SB2 types over the SC type. Only one artefact was shown to be made of obsidian from another source, namely, that on the island of Palmarola, in the Pontine Archipelago. The Monte Arci obsidian were procured in the form of small nodules that were then reduced on site, the knappers primarily producing flakes using an expedient and intensive technology. This tradition involved the production of very few types of formal implements, including geometrics and carving/boring tools, forms that are typical of the Tyrrhenian Cardial Early Neolithic. This is the earliest Neolithic culture on Corsica, whose appearance coincides with a major colonization of both Corsica and Sardinia. The significant presence of Sardinian obsidians in the southwestern Corsican site of Renaghju attests to early contacts between groups inhabiting these islands from the 6th millennium BC, while the Palmarola obsidian indicates occasional contacts with groups living on the Italian Peninsula. Alternatively, this “exotic” raw material’s presence at Renaghju might be viewed as the result of frequent and intensive movements of the first colonists in the Tyrrhenian area.