Background: Bone-grafting materials are required in orthopaedic surgery to treat bone defects. Bone formation assessment is required for the development of new strategies and approaches and for quality assurance and quality control of currently available materials. Approaches to the assessment of bone formation are yet to be systematically established, quantified and standardized. Aims: the overall aim of this study was to establish a set of comprehensive quantitative approaches for the assessment of bone formation and to evaluate the role of osteoblastic cells, growth factors, and scaffolds on this process. Materials & methods: both in vitro and in vivo parameters for osteoblast phenotype and bone formation were tested in osteosarcoma cell lines, Saos-2 and U2OS cells, mesenchymal cell line, C2C12 cells, primary adipose derived stromal cells (ADSCs), platelet rich plasma (PRP), and morselized bone grafts. The in vitro parameters used were measurement of alkaline phosphatase (ALP) activity, detection of bone nodules and biomineralization, and quantification of immunocytochemistry and conventional RT-PCR of osteoblast genotyping. In vivo parameters involved ectopic bone formation in nude mice and nude rats and a tibial defect model in nude rats. Histomorphometric and quantitative immunohistochemical analyses were also performed. Results: The in vitro characterization and ectopic bone formation capabiltity of Saos-2 and U2OS cells have been established. Saos-2 cell line, which presents many osteoblast genotype and phenotype, is a stable positive control for both in vitro and in vivo bone formation assessments. The measurement of ALP activity in both solid and liquid phases has been standardized. Both the genotype and phenotype of osteoblast lineage cells has been quantitatively assessed during the capability testing of ADSCs and PRP. Quantitative assessment of new bone formation and related protein markers in vivo has been successfully established through the testing of the biological properties of gamma irradiated morselized bone grafts. Conclusion: A comprehensive knowledge of the assessment of bone regeneration and formation in vitro and in vivo has been integrated and developed through years of study. A whole set of in vitro and in vivo approaches for the assessment of bone formation has been modified and standardized to best suit the different clinical applications. This thesis provides an outline of both in vitro and in vivo bone formation assessment and their clinical applications.