This is prospective randomized, double blind study designed to evaluate the use of zoledronic acid in the prevention prevention of bone loss post allogenic BMT done for beta-thalassemia major patients.

Inclusion Criteria:

• Signed written informed consent.
• Patients must be 18 years old and over.
• Diagnosed with beta-thalassemia major
• Scheduled for allogenic bone marrow transplantation
• The date of randomization must be no more than 1 week after BMT.
• Patients must be accessible for follow-up.
• Life expectancy of at least 12 months from randomization.

Exclusion Criteria:

• Patients with any clinical or radiological evidence of existing fracture in the lumbar spine and/or total hip.
• Patients with a history of fracture with low-density or no associated trauma.
• Osteoporotic patients with T-score <= -2.5
• Previous treatment with a bisphosphonate.
• Patients with abnormal renal function as evidenced by either a serum creatinine determination 1.5 x or greater above the upper limit of normal or by a calculated creatinine clearance of 30 ml/minute or less.
• Pregnancy and lactation.
• Women of childbearing potential not on a medically recognized form of contraception.
• Subjects who, in the opinion of the investigator, are unlikely to cooperate fully during the study.
• Subjects participating simultaneously in studies with unapproved drugs, indications or treatment regimens.
• Known hypersensitivity to zoledronic acid or bisphosphonates.
• Patients with prior exposure to anabolic steroids, growth hormone, Parathyroid Hormone (PTH) or other drugs known to affect the skeleton (e.g., calcitonin, mithramycin, or gallium nitrate).
• Serious intercurrent illness
• History of metabolic bone diseases
• History of corticosteroid treatment for other causes
• History of antiepileptic drug treatment
• History or surgery at the lumbosacral spine, with or without implantable devices.
• Any disease of the spine that would preclude the proper acquisition of a lumbar spine DXA.
• Mental illness that precludes the patient from giving informed consent.
• Current active dental problems including infection of the teeth or jawbone (maxilla or mandibular); dental or fixture trauma, or a current or prior diagnosis of osteonecrosis of the jaw (ONJ), of exposed bone in the mouth, or of slow healing after dental procedures.
• Recent (within 6 weeks) or planned dental or jaw surgery (e.g.. extraction, implants)