Objective:To evaluate the efficacy and safety of rhPTH(1-34) vs.elcatonin.Methods:Sixty palients with primary OP were randomly divided into two groups according to the ratio of 3:1.rhPTH(1-34) group(PTH group) was treated with subcutaneous injection of rhPTH(1-34) 20 μg daily for 18 months,and the elcalonin group(CT group) was treated with intramuscular injection of elcatonin 20 U weekly for 12 months.Bone mineral density(BMD) of the lumbar spine 2-4(L_(2-4))and femoral neck,serum calcium and phosphorus,urinary calcium,serum hone specific alkaline phosphatase(BSAP).and urinary c-terminal telopeptides of type Ⅰ collagen/creatinine(uCTX-Ⅰ /Cn were tested at baseline,and 6.12.and 18 months after treatment.Results:In PTH group.HMD of L_(2-4),at 6,12.and 18 months,BDM of Femoral neck at 18 month,BSAP at 6 and 12 months and uCTX- Ⅰ /Cr at 6.12 and 18 months were all significantly raised.In CT group.HMD of L_(2-4) at12 month and that of femoral neck at 12 and 18 months were significantly elevated,while HSAP was significantly decreased at 12 and 18 months,and no significant difference on CTX- Ⅰ /Cr was observed.When BMD growth and growth rate between two groups were compared.PTH group had better improvement in L_(2-4) BMD and growth rate than CT group at 6.12.and 18 months.BMD growth and growth rale of femoral neck al 12 month and its growth at 18 month in CT group were higher than in PTH group,hut there was no significant difference between two groups regarding the growth rates at 18 month.Besides,there were no significant differences regarding the rales ol adverse reactions between two groups.Conclusions:rhPTH(1—34),is safe and effective in the treatment of primary OP.It is superior to elcatonin in improving vertebral HMD at onset time,growth rate and growth range,but inferior to elcatonin at HMD of femoral neck. Objective: To evaluate the efficacy and safety of rhPTH (1-34) vs. elcatonin. Methods: Sixty palients with primary OP were divided into two groups according to the ratio of 3: 1. rhPTH (1-34) group group was treated with subcutaneous injection of rhPTH (1-34) 20 μg daily for 18 months, and the elcalonin group (CT group) was treated with intramuscular injection of elcatonin 20 U weekly for 12 months.Bone mineral density (BMD) of The lumbar spine 2-4 (L 2-4) and femoral neck, serum calcium and phosphorus, urinary calcium, serum hone specific alkaline phosphatase (BSAP) .and urinary c-terminal telopeptides of type I collagen / creatinine (uCTX- I / Cn were tested at baseline, and 6.12 and after 18 months treatment. Results: In PTH group. HMD of L_ (2-4), at 6, 12. and 18 months, BDM of Femoral neck at 18 month, BSAP at 6 and 12 months and uCTX- I / Cr at 6.12 and 18 months were all significantly raised. In CT group. HMD of L_ (2-4) at 12 month and that of femoral neck at 12 and 18 months were significant ly elevated, while HSAP was significantly decreased at 12 and 18 months, and no significant difference on CTX-I / Cr was observed. WH BMD growth and growth rate between two groups were compared. PTH group had better improvement in L_ (2-4 ) BMD and growth rate than CT group at 6.12.and 18 months.BMD growth and growth rale of femoral neck al 12 month and its growth at 18 month in CT group were higher than in PTH group, hut there was no significant difference between two groups regarding the growth rates at 18 month.Besides, there were no significant differences regarding the rales ol adverse reactions between two groups. Conclusions: rhPTH (1-34), is safe and effective in the treatment of primary OP. It is superior to elcatonin in improving vertebral HMD at onset time, growth rate and growth range, but inferior to elcatonin at HMD of femoral neck.