Potential toxicity of a bioactive borate glass was evaluated using in-vivo animal models in soft tissue and bone and in-vitro cell culture using MLOA5 late osteoblast/early osteocytes cells. No toxicity was found between bioactive borate glass and subcutaneous tissue, in the liver, and only normal incidental changes in rat kidney. Bone growth across porous scaffolds composed of randomly oriented borate glass fibers was significantly higher than for a scaffold composed of a borosilicate or a silicate bioactive glass (13-93) fibers after 12 weeks in-vivo, p<0.05. In-vitro cell culture on bioactive glasses showed that under static culture conditions, borate glass disks tended to inhibit the growth of MLOA5 cells. The present work, along with literature data, show that bioactive borate glasses are biocompatible in-vivo and are not toxic to adjacent hard or soft tissues, or internal organs such as the kidney and liver, at the relatively high, estimated concentrations (<~126mg/kg/day). Based on the present results and literature data, ions released from the borate glasses such as alkali or boron were not toxic in a dynamic environment such as the body and should be considered for use in humans and other mammals for soft and hard tissue engineering applications.