Aims: In a recent study, chemical microroughening of bioactive glass surface was shown to promote attachment of osteoblastic cells and osseointegration of porous bioactive glass implant. The current in vivostudy employed molecular biologic techniques to clarify the osteogenic effects of smooth and microrough glass surfaces. Methods:Using a rat model, a portion of the medullary canal in the proximal tibia was evacuated and filled with microroughened or smooth bioactive glass microspheres. The primary bone healing response and subsequent remodelling were analysed at 1, 2, and 8 weeks, respectively. The expression of various genes for the bone matrix components (type I collagen, osteocalcin, osteopontin, osteonectin) and proteolytic enzymes (cathepsin K, MMP-9) were determined by Northern analysis. Results: The microroughened bioactive glass microspheres were found to induce higher mRNA levels for osteopontin and lower levels for osteonectin at 2 weeks after operation when compared to smooth control micropheres. At 8 weeks, the MMP-9 expression levels were significantly higher with microroughened bioactive glass microspheres. Conclusion: Microroughening of the bioactive glass surface triggered temporal changes in the expression of specific genes.