We used microcomputed tomography (micro-CT) to evaluate the effects of basic fibroblast growth factor (FGF-2) contained in absorbable collagen sponges on angiogenesis and bone regeneration in rat calvarial non-critical-size bone defects. Two symmetrical non-critical-size calvarial bone defects (diameter, 2.7 mm) were created in male Fisher rats. An absorbable collagen sponge with or without FGF-2 (0.1% or 0.3%) was implanted into each defect. Blood vessel volume and bone volume were calculated using software. On day 28, blood vessel volume and bone volume were significantly greater in the 0.3% and 0.1% FGF-2 groups than in the control group. FGF-2 concentration-dependently increased blood vessels and bone formation in non-critical-size bone defects in rat calvaria.