Porous conical implants made by sintering micro-spheres made from bioactive and bio-compatible glasses have been tested mechanically as well as in vivo by inserting the implant through the cortical bone into the bone marrow. The behaviour is compared to a reference implant made by sintering micro-spheres of metallic titanium. Due to capillary forces the implant pores were filled with bone marrow fluid when inserted. An extended bone ingrowth occurred in the cones of bioactive glass, in the titanium ones only in the cortical area. Further, the factors influencing the formation of a chemical bond between glass and living tissue are discussed.