A method for the study of in vivo corrosion of various dental materials such as amalgams, gold, and chromium–cobalt alloys combining implantation and nuclear tracer techniques is described. Radioactive and nonradioactive implants were inserted subcutaneously in the backs of two groups of rats. After 5 days all animals were killed. The adjacent tissue was submitted to histopathological examination. The animals exposed to radioactive amalgams and chromium-cobalt disks with activity levels of 2—4 mCi showed local tissue reactions identical to those seen in sham-operated animals—-that is, inflammation and formation of granulation tissue. In contrast, the rats exposed to radioactive gold foils with activity levels of about 20 mCi suffered heavier damage at the implantation site, with loss of hair and some necrosis, in addition to the inflammation and granulation tissue formation. There was no kidney damage. The release of mercury, gold, or cobalt into the adjacent tissue and the kidney was measured by means of gamma-ray spectrometry.