Objective:To investigate the effect of human parathyroid hormone(PTH)on alveolar bone of ovariectomized(OVX) rats. Methods:Sixty female 5-month-old rats were divided into three groups randomly,two groups,which were ovariectomized and developed into osteoporotic models,were named as PTH treated group(PTH group) and the control group(OVX group). Another group was sham ovariectomized(sham-OVX) as the blank control group(sham-OVX group). Six weeks later,the PTH group was injected with recombinant human parathyroid hormone(1-34)[rhPTH(1-34)]once daily for forty days,while the other two groups were injected with saline. Then they were sacrificed and their mandibles were separated respectively for radiological imaging,histomorphological observation and osteoclastic cell couting. Results:The radiological imaging analysis showed that the loss of the distal alveolar bone of the first molar in OVX group was more than that of either PTH group or sham-OVX group[(1.34 ± 0.89)mm vs. (0.78 ± 0.62)mm,(0.67 ± 0.54)mm],both P < 0.05. Meanwhile,the histomorphological observation suggested that the bone of OVX group was absorbed more than the other two groups. Besides,the cell counting results indicated that OVX group had more osteoclast than both PTH group and sham-OVX group(38.6 ± 20.2 vs. 23.3 ± 13.0 and 25.0 ± 11.4 respectively,both P < 0.01),which showed significant statistical differences. Conclusion:The absorption of alveolar bone of the osteoporotic rats can be inhibited by PTH.