OBJECTIVE To investigate the therapeutic effect of recombinant human parathyroid hormone(1-34) [rhPTH(1-34)] on osteoporosis of ovariectomized rats. METHODS The model of osteoporosis was formed after 3 months of ovariectomy with 6-month age of 80 rats. Another 20 rats was control of sham operation. rhPTH(1-34) was subcutaneously injected once daily with 5, 10, 20, 40 micrograms/kg for 3 months. There were 10 rats in each group. The control of therapy included Salmon Calcitonin to 10 rats and Alendronate sodium to 10 rats. The bone weight of dry and ash, bone mineral density, bone biomechanical property, trabecular area, bone mineral deposition and serum alkaline phosphatase, Ca, P and urinary Pyridinoline/creatin (Pyd/Cr) were measured after the end of therapy. RESULTS When administered to animals as a single subcutaneous injection once daily, rhPTH(1-34) increased obviously bone mass, bone biomechanical property and trabecular area, as well as bone deposition compared with the animals of control group. The bone architecture was ultimately improved by rhPTH(1-34) therapy. CONCLUSIONS Rats of ovariectomized-induced osteoporosis possess obvious effect of treatment with low dose of rhPTH(1-34) administered once daily.