Two corn. dental Co-Cr-Mo-W-Si-Fe-Ce (I) and Ag-Au-In-Pt (II) alloys were studied for corrosion resistance in 0.9% NaCl soln. at room temp. for 1 week and for 4 mos. The test samples (rods) were prepd. by smelting the alloys as recived or in mixt. with recycled ones. The concns. of metals in the test solns. were detd. by the title methods. The corrosion resistance of the I alloy decreased with the increasing amts. of recycled alloys. In the case of II alloy, no deterioration of corrosion resistance was obsd. after addn. of the recycled alloy.