The purpose of this study is to test how well higher doses of lanthanum carbonate reduce the pre-dialysis level of serum phosphorus in subjects undergoing dialysis due to end stage renal disease.

Inclusion Criteria:

• Subjects with ESRD who currently require treatment for hyperphosphatemia
• Women of childbearing potential must have a negative serum beta HCG pregnancy test and must agree to abstain from sexual activity or to use acceptable contraceptives from the time of informed consent throughout the study

Exclusion Criteria:

• Treatment with compounds containing calcium, aluminum or magnesium for use as a phosphate binder
• Hypocalcaemia
• Treatment-naive to any phosphate binder with a serum phosphorus < 5.5 mg/dL
• Any significant gastrointestinal surgery or gastrointestinal disorders