Osteoporosis can be categorized into primary and secondary types, with glucocorticoidinduced osteoporosis (GIOP) being the most common form of secondary osteoporosis and the third most prevalent overall. This study explores the anti-osteoporosis effects of zinc oxide nanoparticles (ZnO NPs) and nano-hydroxyapatite (HA NPs) in a rat model of dexamethasone (DEX)-induced osteoporosis. Nanoparticle characterization was conducted using various techniques to evaluate size, shape, and chemical composition. A total of 48 adult female Swiss albino rats were divided into six groups (n= 8). Osteoporosis was induced in Groups II–VI with DEX (7 mg/ kg, IM) weekly for 5 weeks. Subsequently, treatments were administered for 3 months: Group I (negative control), Group II (DEX-induced OP), Group III (alendronate (1 mg/kg) weekly), Group IV (ZnO NPs (0.50 mg/kg) monthly), Group V (HA NPs (8 mg/ kg) monthly), and Group VI (combination (ZnO NPs/ HA NPs) IV monthly). Serum samples were analyzed for bone metabolism markers—including cross-linked C-telopeptide of type I collagen (CTX-1), tartrateresistant acid phosphatase 5b (TRACP-5b), alkaline phosphatase (ALP), calcium (Ca2⁺), and phosphorus (P). Molecular analysis and histopathological assessment of femurs were performed. Results indicated that treatment with ZnO NPs or HA NPs significantly up-regulated Runt-related transcription factor-2 (RUNX-2) expression; decreased serum CTX-1, TRACP-5b, and ALP levels; and increased Ca2⁺ and P levels, thereby promoting bone mineralization and ameliorating DEX-induced histological alterations in bone tissues. Notably, the combination treatment of ZnO NPs and HA NPs exhibited superior effects due to synergistic actions. This study highlights the promising anti-osteoporosis potential of ZnO NPs and HA NPs, both individually and in combination, for the treatment of dexamethasone-induced osteoporosis.