Background: Control of serum phosphate over the long term is essential in patients with end-stage renal disease. Six-month and 2-year extensions to a 6-month study evaluated the long-term safety, tolerability and efficacy of the new phosphate binder lanthanum carbonate. Methods: Patients who participated in a 6-month, randomized trial comparing lanthanum carbonate with calcium carbonate were eligible for a 24-week, open-label extension. Lanthanum carbonate-treated patients continued taking their established maintenance dose (‘continued-lanthanum group’) and calcium carbonate-treated patients switched to lanthanum carbonate, 375–3,000 mg/day (‘switch group’). Patients could also enter a further 2-year extension. Efficacy parameters, including serum phosphate, were monitored. Results: Mean serum phosphate was ∼1.80 mmol/l throughout the trial. The percentage of patients with controlled serum phosphate (≤1.80 mmol/l) after the 6-month extension was 63.3 and 58.4% in the continued-lanthanum and switch groups, respectively; after the 2-year extension, 54.4% of patients had controlled serum phosphate. After discontinuation of calcium carbonate and initiation of lanthanum carbonate, the hypercalcemia incidence was 2.7%, compared with 20.2% during the double-blind phase. Calcium × phosphate product was maintained at an acceptable level. Lanthanum carbonate was well tolerated; adverse events were mild/moderate and mainly gastrointestinal. Conclusions: Lanthanum carbonate maintains effectiveness with continued tolerability for up to 3 years.