There is adequate evidence that dental amalgam restorations, during and after placement, results in the release of Hg into the patient's body. Whether the Hg released from amalgam is due to placement procedures, surface abrasion, or later corrosion breakdown, there is evidence that a low level Hg release continues for years. It is generally agreed that if amalgam was introduced today as a restorative material, they would never pass F.D.A. approval. With new and more accurate techniques of measuring Hg levels, especially in tissue and blood, additional studies are necessary to relate blood-Hg levels with dental amalgam restorations. Studies must relate existing restorations as well as the placement of new restorations to body-Hg levels. It is possible that we have accepted a potentially dangerous material as being safe.