Electroless nickel plating is an important process in the fabrication of metal microstructures on silicon substrates. Adhesion of the metal film to the substrate is a key parameter. We report a study of the adhesion of electroless nickel plating on polished silicon for different surface treatments (prior to plating), substrate areas and plating durations. Three different surface treatments considered are: mild etching, palladium activation and nickel activation. Adhesion strength in excess 9.8 × 107N / m2 has been obtained. Adhesion requirements for using nickel plating for masking the silicon substrate during anisotropic etching is also discussed.