OBJECTIVE To find the optimal scaffold for tissue-engineered bone, one approach is to test existing biomaterials on their suitability as scaffolds. In this study, the suitability of different alloplastic and xenogenic biomaterials as scaffolds for ex vivo osteoblast cultivation was investigated. METHODS Normal human osteoblast cells were cultured on the surface of bovine collagenous materials, bovine hydroxyapatite, porcine gelatin, synthetic polymer, and collagen-containing bovine hydroxyapatite, and the investigation of proliferation was performed after 24, 72, and 120 hours. Measurement of the differentiation marker alkaline phosphatase and osteocalcin was made after 20 days of incubation. RESULTS The obtained data showed significantly higher proliferation and differentiation rates in cells cultivated on collagen-rich biomaterials in comparison to noncollagenous or collagen-poor biomaterials (P < .05). CONCLUSIONS In tissue engineering the scaffold should be biocompatible and serve as a proper matrix for the cells to produce the new structural environment of extracellular matrix ex vivo. Collagen supports initial cell attachment and cell proliferation, allowing immature osteogenic cells to differentiate into mature osteoblasts, but collagen may not be the only dominating factor for cell-matrix interaction during ex vivo bone formation. CONCLUSIONS These data suggest that a 3-dimensional collagen matrix can provide a more favorable environment for the attachment, proliferation, and differentiation of in vitro osteoblastlike cells, at least until the initial stage of differentiation, than noncollagenous biomaterials.