Summary This multicenter and randomized clinical trial showed that daily oral herbal formula Xian Ling Gu Bao (XLGB) was safe in postmenopausal women over a 1-year treatment.Those patients (n~50) treated with XLGB at the conventional dose demonstrated a statistically significant increase in dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) at lumbar spine at 6 months and a numerically increased BMD at 12 months.Introduction The aim of this study was to examine the safety and efficacy of a herbal formula XLGB in postmen opausal women (ChiCTR-TRC-00000347).Methods One hundred eighty healthy postmenopausal women (≥60 years old) with BMD T-score≤-2.0 (lumbar spine or femoral neck) were recruited fiorm four clinical centers to receive low-dose (conventional dose) XLGB (L-XLGB group, 3 g/day, n=61) or high-dose XLGB (H-XLGB group, 6 g/day, n=55) or placebo (CON group, n=61).Women received daily calcium (500 mg) and vitamin D (200 IU) supplementation.Primary endpoints were lumbar spine BMD and safety; secondary endpoints were femoral neck BMD and bone turnover markers measured at baseline and at 6 and 12 months.Results Of 180 women recruited, 148 completed the study.The compliance in iach group was comparable.Prominent adverse events were not observed in either group.in the L-XLGB group at 6 months, lumbar spine BMD by DXA increased significantly from baseline (+2.11% versus CON +0.58% p<0.05), but femoral neck BMD did not; at 12 months, BMD in the L-XLGB group decreased from 6-month levels yet remained higher than baseline, but without difference from the CON group.There was no dose-dependent response.Bone turnover marker levels declined diuing the tist 6 months after XLGB treatment.There was no significant difference in the overall incidence of side effects among treatment and control groups.Conclusion XLGB over 1-year treatment at the conven tional dose demonstrated safe and only a statistically significant increase in BMD at lumbar spine at 6 months in postmenopausal women.