Total Reflection X-Ray Fluorescence Analysis (TXRF) is presented as a new analytical tool which allows to assess the metal contamination on silicon wafer surfaces in a non-destructive way. The technique uses a conventional X-Ray tube with a Mo anode, an energy-dispersive Si(Li) spectrometer, and an alignment set-up for the exact control of the angle of incidence which is kept below the critical angle for total reflection. Detection limits in the order of 100 ppm of a monoatomic layer are achieved e.g. for transistion metals. Application studies include plating of metals from a high purity liquid process chemical (BHF) and the adsorptivity of the silicon surface for Br originating from RCA type cleaning procedures.