<p>The current study attempted to investigate the effect of hydroxyapatite nanofibers (HANFs) added in different percentages upon the qualities of glass ionomer cement (GIC): fracture toughness, vickers microhardness and fluoride release. Synthesis and characterization of hydroxyapatite nanofibers were carried out before being added to the powder of high-viscosity conventional GIC in three varied weight ratios (1, 3 and 5%) resulting into 3 experimental groups which were next compared with basic GIC as a control group. Fracture toughness, Vickers microhardness and fluoride release on day1 and day 7 were evaluated. Results indicated significant improvement in fracture toughness, microhardness and fluoride release of GIC modified by hydroxyapatite nanofibers at varied tested ratios and this increase was directly proportional to their ratio of addition. According to these findings, glass ionomer cement modified with hydroxyapatite nanofibers in varying proportions could be a dependable restorative material with enhanced fracture toughness, microhardness and fluoride release.</p>