The present study investigated the effects of variations in decalcification time of demineralized freeze-dried bone on the osteogenic potential of DFDB. Sixteen 3-wall intrabony defects with 4mm depth were surgically created in the mesial aspect of upper and lower anterior teeth of 4 dogs. Following the flap procedure, three test groups with 4 defects each received either freeze-dried bone graft (Group I), demineralized freeze-dried bone graft decalcified for 12hours (Group II), or demineralized freeze-dried bone graft decalcified for 24hours(Group III). The rest of the four defects received the flap procedure-only as the control group. The healing was histologically analyzed after 14 weeks on the length of connective tissue adhesion, new bone formation and new cementum formation. The results were as follows: 1. The length of connective tissue adhesion showed no statistically significant difference in all groups with 0.62±0.14mm for Control, 0.42±0.11mm for Group I, 0.63±0.43mm for Group II and 0.52±0.11mm for Group III. 2. The new bone formation showed no statistically significant difference in all groups with 3.17±0.24mm for Control. 3.15±0.56mm for Group I. 3.22±0.36mm for Group II, and 3.28±0.74mm for Group III. 3. The new cementum formation showed no statistically significant difference in all groups with 4.19±0.46mm for Control, 3.23±0.64mm for Group I, 4.13±1.82mm for Group II. and 3.13±0.62mm for Group III.