The item of the paper is focussed on some bio-compatible coatings for rare earth based permanent magnets, which are used as dental materials for prosthetic devices as retention units. The studied alloy belongs to Nd-Fe-B system with some Dy and Al content. The double-layer coatings had different chemical compositions; first layer: Ag30-Cr70, Co30-Cr70, Stainless Steel and the second layer: titanium nitride (TiN). Data about corrosion behavior, wear resistance and adhesion are presented. The corrosion resistance of these coatings was tested in artificial saliva, using electrochemical potentiostatic and potentiodynamic polarization techniques. The stability in the corrosion media, the localized corrosion susceptibility and the corrosion rates were determined. It resulted that the Nd30-Dy5-Fe-Al0.4-B alloy with Ag30-Cr70 + TiN film is very stable in artificial saliva. The wear behavior of the coatings in different conditions of contact and load was tested, also. The adhesion was determined by scratching test.