Nanoparticles of strontium-hydroxyapatite (SrHA) loaded with zoledronic acid (ZOL) were prepared. ZOL was used as a carrier to deliver SrHA nanoparticles to bones. SrHA/ZOL nanoparticle based drug formulation was tested in a rat model of postmenopausal osteoporosis. SrHA/ZOL therapy showed significant improvement in bone properties.