INTRODUCTION: To analyze the effects of intravenous pamidronate (APD) on bone remodelling, bone mineral density (BMD), fractures and bone mineral metabolism parameters, and the rate of adverse events, with special attention to renal function, in patients with osteoporosis with intolerance and/or any contraindication to oral bisphosphonates. METHODS: We analyzed prospectively 17 osteoporotic patients (age, 66.8 +/- 9.4 years): 65% women, 82% with prevalent vertebral fractures. All patients received APD therapy (30 mg intravenously every 3 months) and were followed up for 1 year. We analyzed serum amino-terminal propeptide of type I procollagen and urinary N-terminal cross-linked telopeptide of type I collagen (as markers of bone turnover), serum calcium, phosphate, parathormone, 25OH-vitamin D, creatinine, and the creatinine clearance: at baseline, 1 week after starting APD treatment, and thereafter for every 3 months (before infusion) during 1 year. We also analyzed lumbar and femoral BMD at baseline and after 1 year, the incidence of new fractures, and the treatment-related adverse events. RESULTS: One week after starting APD treatment, a significant decrease of N-terminal cross-linked telopeptide of type I collagen (32%) (P < 0.05) and an increase of parathormone values (72%) (P < 0.01) were observed, without significant differences found thereafter. No significant differences were observed in BMD evolution and in the other parameters analyzed throughout the study, nor in impairment of renal function. Sixty-four percent of patients suffered new skeletal fractures, 41% of patients showed flu-like syndrome after APD infusion, and 1 patient was withdrawn from treatment because of adverse events. CONCLUSION: Patients with severe osteoporosis receiving APD infusions had a high rate of fractures without significant changes in bone mass or in bone markers; nevertheless, such a therapeutic regimen showed a good renal safety profile, suggesting that APD at this dosage is safe but ineffective for treating severe osteoporosis.