The effect of therapeutic agents on trabecular bone loss in the mandible was investigated in ovariectomized rats. Eighty-seven Wistar SPF female rats were ovariectomized (OVX) or given a sham operation (Sham), and maintained on a diet containing 0.1% calcium. Four weeks later, groups of OVX rats were treated with estriol (E3), calcitonin (CT), etidronate, or 2-carboxyethylgermanium sesquioxide (Ge-132). The Basal group was maintained on a diet containing 1.0% calcium, and the OVX and sham groups on a diet containing 0.1% calcium. The trabecular bone mineral density (BMD) and trabecular bone mineral content (BMC) in 11 mandibular slices from 0.5 mm at the mesial margin of the first molar to 0.5 mm at the distal margin of the third molar, were measured using peripheral Quantitative Computed Tomography (pQCT). The BMD in the OVX group was lower than that in the Sham group, and decreased BMC was observed only in the molar region. BMD and BMC were increased in the etidronate-treated group, but only BMC was increased in the CT group. E3 treatment increased BMD and BMC; significant increases were also observed beneath the molar. Ge-132 treatment increased both BMD and BMC, especially the latter.