Zoledronic acid is a third-generation bisphosphonate that is administered as an annual infusion, and it has some interesting features. After a successful preclinical development program, it has undergone extensive testing in postmenopausal osteoporosis where it has substantial antifracture efficacy at the vertebral, nonvertebral, and hip sites. It has been shown to be effective in reducing vertebral and nonvertebral fractures in patients who had recently suffered a femoral neck fracture, and has demonstrated efficacy in preventing and reversing bone loss in glucocorticoid osteoporosis. The drug is generally well tolerated, although it has been shown to cause significant acute phase reactions occurring in the first 3 days, mainly after the first infusion. Care must be taken to avoid using the drug in those with significantly impaired renal function, although initial concerns about a relationship to atrial fibrillation and osteonecrosis of the jaw have so far proved to be unfounded.