The substance loss from four commercially available Ni-Cr-Mo and four Co-Cr-Mo alloys was examined using a solution of 0.1 mol/L lactic acid and 0.1 mol/L sodium chloride. Dissolved ions were analyzed over a 5-week period using atomic absorption spectroscopy. The results revealed a considerable range of corrosion rates among the Ni-Cr-Mo alloys, with average values after 35 days between 0.54 and 3,261 micrograms/cm2, while the distribution of values for the Co-Cr-Mo alloys was not as wide - between 0.43 and 34.9 micrograms/cm2.