The aim of this study was to evaluate the efficacy of intravenous pamidronate in patients with transient osteoporosis of the hip (TOH). Thirteen men and three women (mean age 38.3 years, range 30-49) were recruited. The diagnosis was made by means of radiographs, bone scintigraphy, and magnetic resonance imaging (MRI). Pamidronate (45 mg) was intravenously administered three times, once every third day. The outcome measures included a clinical assessment using a pain visual analog scale (VAS; range 0-100), and the WOMAC functional impairment score (FUI; range 0-100). The bone mineral density (BMD) of the total hip and femoral neck was measured using dual-energy X-ray absorptiometry (DXA). Clinical assessments were made before treatment (T(0)) and 1 month later (T(1)), and the densitometric measurements at T(0), and then after 2 (T(2)) and 4 months (T(4)). A further MRI scan was made 3 months after treatment. In comparison to the unaffected side, there was a significant decrease at T(0) in the BMD of both the total hip (median 16.6%, range 8.5%-29.1%, p < 0.00001) and femoral neck (median 22.5%, range 12.0%-34.2%, p < 0.00001). By T(1), both VAS and FUI had decreased significantly (p < 0.00001). By T(2), the total hip and femoral neck BMD had increased by 10.9% (range 2.7%-23.6%, p < 0.00001) and 12.3% (range 7.8%-26.9%, p < 0.00001), respectively, and all patients were asymptomatic. By T(3), the MRI findings had normalized in all patients and, at T(4), there was a further increase in BMD. None of the patients experienced symptom relapse during the follow-up of 39.5 +/- 17.7 months. These results suggest that a short course of pamidronate is effective in treating TOH, and leads to a prompt and long-lasting recovery.