An innovative anti-osteoporosis herbal formula containing Epimedii Herba, Ligustri Lucidi Fructus and Psoraleae Fructus (ELP) has been previously shown its bone protecting effects in ovariectomized osteoporotic rats and also in post-menopausal osteopenic women. This study aimed to investigate the efficacy of ELP against bone loss during physical inactivity or weightlessness. A hindlimb unloading tail-suspended rat model was used for studying the effects of ELP on bone mineral density (BMD) and bone micro-architecture. For in vitro mechanistic studies, rat mesenchymal stem cells (MSCs) and mouse macrophage cells (RAW264.7) were used for studying the effects of ELP on osteogenic/adipogenic differentiations and osteoclastogenesis, respectively. Our data illustrated that ELP had a significant preventive effect against bone loss induced by tail-suspension (TS) at day 28 (p < 0.01) as indicated in the reduction in BMD loss and the preservation of bone micro-architecture. ELP could significantly promote the osteogenesis and suppress the adipogenesis (p < 0.05) in MSCs. Besides, significant inhibition of osteoclast formation (p < 0.01) was found in ELP-treated RAW264.7 cells upon receptor activator of nuclear factor kappa-B ligand induction. Our study presents the first scientific evidence that ELP had a significant preventive effect against bone loss induced by TS through the actions of enhancing osteogenesis, suppressing adipogenesis and osteoclastogenesis. Copyright © 2012 John Wiley & Sons, Ltd.