OBJECTIVE: To compare the effects of strontium ranelate and PTH (1-34) on bone quality of ovariectomized rats. METHODS: 80 SD rats were randomly divided into sham operation group (group A, n=10) and dual ovariectomy (group B, n=70). 3 months after operation, group B were randomly divided into 7 groups, with 10 rats in each group. B0 group were given normal saline [0.9 g/(kg·d)] subcutaneously; B1-B3 groups were given low-dose, medium-dose and high-dose of strontium ranelate [0.45, 0.9, 1.35 g/(kg·d)] intragastrically; B4-B6 groups were given low-dose, medium-dose and high-dose of PTH (1-34) [30, 60, 90 μg/(kg·d), treated for 5 days, rested for 2 days] subcutaneously. Group A was same to group B0 in therapy regimen. All rats were sacrificed 8 weeks later. The contents of P1NP and CTX-1 in serum of rats were determined by ELISA assay; bone density of 4th lumbar vertebrae was detected by bone densitometer; BV/TV, Tb.Th, Tb.N and Tb.Sp were detected by CT; maximal load and elastic modulus of 5th lumbar vertebrae were measured by compression test. RESULTS: Compared with group A, the serum levels of P1NP and CTX-1 in B0-B6 groups increased significantly, while bone density of 4th lumbar vertebrae, maximal load and elastic modulus of 5th lumbar vertebrae decreased significantly in B0-B3 groups (P<0.05); BV/TV level of 4th lumbar vertebrae decreased significantly, while Tb.Sp level increased significantly in B0 group (P<0.05). Compared with B0 group, bone density of 4th lumbar vertebrae, maximal load and elastic modulus of 5th lumbar vertebrae increased significantly in B1-B3 groups (P<0.05); P1NP content, BV/TV, Tb.N level, bone density of 4th lumbar vertebrae, maximal load and elastic modulus of 5th lumbar vertebrae increased significantly in B4-B6 groups, and were higher than in B1-B3 groups (P<0.05). Tb.Sp level of B1-B6 groups decreased significantly and were lower than those of B1-B3 groups (P<0.05). There was no statistical significance in Tb.Th level among 8 groups and CTX-1 content among B0-B6 groups (P>0.05). CONCLUSIONS: PTH(1-34) is better than strontium ranelate in inhibiting bone loss, improving vertebral bone micro-structure and biomechanical properties of ovariectomized rats.