To examine the effects of Panax notoginseng saponins (PNS), the main active components of Panax notoginseng, on ovariectomy-induced osteoporosis in rats. A total of 72 six-month-old female rats were randomly assigned to sham-operated group and five ovariectomized (OVX) groups:OVXwith distilled water (5 ml/kg/day, p.o.), OVXwith graded doses of PNS(75, 150, 300 mg/kg/day, p.o.), and OVX with nilestriol (1 mg/kg/week, p.o.). Animals were sacrificed after a 13-week treatment course. Compared with the OVX group, PNS administration prevented OVX-induced decrease in bone mineral density (BMD) of lumbar vertebrae and total femur, and significantly increased bone structural biomechanical properties. Improvements of BMD and biomechanical properties were accompanied by the beneficial changes of PNS on trabecular microarchitecture in the tibial metaphysis. PNS at the highest dose significantly prevent decrease in trabecular bone volume over bone total volume, trabecular number, trabecular thickness, connectivity density, and increase in trabecular separation and structure model index inOVXrats. The bone-modulating effects of PNS may be due to the increased bone formation and decreased bone resorption, as was evidenced by the elevated level of serum alkaline phosphatase and decreased level of urinary deoxypyridinoline. PNS treatment is able to enhance BMD, bone strength, and prevent the deterioration of trabecular microarchitecture without hyperplastic effect on uterus. Therefore, PNS might be a potential alternative medicine for the prevention and treatment of postmenopausal osteoporosis. © The Japanese Society of Pharmacognosy and Springer 2010.