To investigate the bone regenerative effect of polymer and collagen incorporation to synthetic bone graft materials.The bone ingrowth of biphasic graft materials was tested in a rabbit calvaria defect model after chemical characterization: HA/TCP (25%/75%) with collagen, HA/TCP (25%/75%) without collagen, (HA/TCP)/PLGA (85%/15%) with collagen, (HA/TCP)/PLGA (65%/35%) with collagen and a commercially available (HA/TCP)/PLGA (50%/50%) (ReOss™, Intra-Lock International, Boca Raton, FL) was used as control. After 4 and 8 weeks, the retrieved samples were subjected to histomorphometrical analysis.Histomorphometry presented no significant differences concerning the bone formation between the different groups at both 4 and 8 weeks. Evidently, the (HA/TCP)/PLGA (65%/35%) with collagen presented the least amount of soft tissue incorporation within the defect. The same group possessed higher amounts of bone graft material within the defect throughout the 8-week observation period, whereas the other groups seemed to decrease in volume from 4 to 8 weeks.Changing the PLGA percentage to 35% within the biphasic graft material seemed to maintain its volume and prevented soft tissue migration, which could be clinically beneficial.