Nineteen beagles (8.8 +/- 0.1 months, 8.5 +/- 0.2 kg, mean +/- SEM) were oophorectomized (OX) at the beginning of the study. The dogs were randomly allocated into three groups: control group (OX, n = 5), OX+clodronate 20 mg/kg orally group (OX + 20, n = 7) and OX+clodronate 40 mg/kg orally group (OX + 40, n = 7). Clodronate administration began the day following oophorectomy and was continued for eight months. Bone mineral density (BMD) was evaluated by dual energy X-ray absorptiometry (DEXA) at baseline and at four and eight months and by quantitative computed tomography (QCT) at baseline and at eight months. Bone biopsies were taken at the beginning and at the end of the study. The change in BMD (g/cm2) during eight months was +2.0% (NS) in OX, +2.3% (NS) in OX + 20 and +10.0% (P < 0.01) in OX + 40 group when measured by DEXA, QCT revealed the same results but in a lesser extent. There were no differences in static and dynamic histomorphometric parameters between the groups at the end of the study. In conclusion, clodronate at a dose 40 mg/kg/day orally increases BMD in young oophorectomized dogs.