Loaded prestressed implants of dense hydroxyapatite and non-loaded hydroxyapatite-coated titanium implants were placed in edentulous regions of the lower jaw of dogs. After 6 month the jaw specimens were fixed and embedded in methyl-methacrylate. Thin non-decalcified ground sections were made for histology. Although the hydroxyapatite showed histological differences between the coated implants and the prestressed solid ones, both had an extensive apposition of normal lamellar bone on the whole surface of the bone-buried part of the implant. The bone contact was very intimate and without any visible intermediate tissue layer. The tissue response observed forms a good biological base for the clinical application of hydroxyapatite-coated titanium implants.