To prevent hip fracture patients for having another fracture, secondary fracture preventing medication should be given as soon as possible. Zoledronate is the most efficient bisphosphonate and is given as an intravenous infusion once yearly. However, the appropriate time to initiate zoledronate treatment after a hip fracture has not yet been established. To clarify the optimal timing of zoledronate to hip fracture patients we have designed a double-blinded, placebo-controlled randomized non-inferiority trial to compare if zoledronate administered early (within 5 days) after hip fracture surgery is as good as zoledronate given late (3 months) after hip fracture surgery.