A fast multi-elemental method of measuring the platinum group elements (PGEs) in geological samples is needed for the geochemical study and the commercial exploitation of these metals. The application of particle induced X-ray emission (PIXE) for the determination of ng-range concentrations of platinum, palladium, rhodium and ruthenium in terrestrial rocks is described. The PGEs are inhomogeneously distributed in sulphide ores and their host rocks, necessitating the analysis of large sample aliquots to obtain representative results. Preconcentration of the sample material is therefore essential for their analysis by PIXE. The noble metals are extracted from a 50 g sample by a modified nickel sulphide fire-assay technique. The resulting NiS button is partly dissolved in hydrochloric acid and the insoluble noble metal sulphides are retained on a Nuclepore filter membrane which is then used directly as a target for PIXE analysis. The method was evaluated by the analysis of serially diluted samples of a standard reference material of a platinum bearing ore. X-ray spectrum optimisation was investigated using differential X-ray absorbers. Detection limits of ∼ 0.5 ng/g were established for the elements Rh, Ru, Pd and Pt. The low detection limits and relative simplicity of analysis by PIXE compare favourably with other recently developed procedures.