In vivo bone regeneration can be achieved either by transplantation of osteogenic cells differentiated from adipose-derived stem cells (ADSCs) or by delivery of exogenous bone morphogenetic protein-2 (BMP-2). In this study, we compared the osteogenic potential between ADSCs and BMP-2 in a mouse calvarial defect model. Critical- sized circular calvarial defects were made in nude mice. The mice were randomized into 4 groups (n=6 per group) that were treated with either 1) fibrin glue alone, 2) fibrin glue with BMP-2, 3) fibrin glue with undifferentiated ADSCs, or 4) fibrin glue with osteogenically differentiated ADSCs. Specimens were harvested at 8 weeks after treatment and evaluated radiographically and histologically. Differentiation of human ADSCs prior to transplantation did not affect bone regeneration. Transplantation of ADSCs was not superior to BMP-2 delivery for in vivo bone formation in a mouse calvarial defect model.