Patients who have been treated with Fosrenol for a minimum of 12 consecutive weeks and are receiving dialysis will be followed for 5 years to compare mortality, bone fractures and incidence of selected morbidities to patients with no lanthanum exposure and to patients being treated for hyperphosphatemia with any marketed product.

Inclusion Criteria: Test Group

• Signed informed consent
• Patient must have ESRD and be receiving dialysis
• Prior treatment with Fosrenol for a minimum of 12 consecutive weeks
• Primary payer of healthcare must be Medicare (patient must supply Medicare Claim Number)
• Patient must be 18 years of age or older

Exclusion Criteria: Test Group

• Patients that do not meet inclusion criteria

Patients for the Historical Control and Concomitant Therapy Groups will be selected from the United States Renal Data System (USRDS). The Test Group will consist of patients who have had a minimum of 12 consecutive weeks of exposure to Fosrenol (lanthanum carbonate).