A new biodegradable adhesive(LYDEX) which is based on Schiff base formation had developed. LYDEX is easy to control the setting time and degradation speed and it has no risk of infection. In the previous study, LYDEX showed high bonding strength and low cytotoxicity in vitro. In the present study, good bone repair was seen in rat bone defect models, especially in rapidly degrading type. On the other hand, slowly degrading type kept its shape longer without excessive inflammation. In rabbit critical defect model with hydroxyapatite granules (HAs), more newly formed bone was seen in rapidly degrading group and hydroxyapatite group, in 3weeks. In 6weeks, more new bone was seen in slowly degrading type group, whereas, almost no new bone was seen in deep area of the fibrin group, in 12weeks. Direct bonding between HAs and bone was seen in HA group and LYDEX groups. These findings suggest that LYDEX with hydroxyapatite granules can be a promising bone substitute.