OBJECTIVES: No research has comprehensively examined the cost-effectiveness between the phosphate binders within the CKD marketplace.   Therefore, a model was developed to evaluate the cost-effectiveness of Fosrenol® (lanthanum carbonate), relative to other second tier agents, Renagel®/Renvela® (sevelamer hydrochloride/ sevelamer carbonate), for the treatment of hyperphosphatemia in CKD. METHODS: A cost-effectiveness model was constructed from a managed care perspective.  Two different time horizons including 1 day and 1 year were considered.  Model inputs were AWP, DACON, phosphate binding capacity, and percent of patients with phosphorous control.  Comparators included lanthanum carbonate (1,000 mg), sevelamer hydrochloride (800 mg), and sevelamer carbonate (800 mg).  Model outcomes consisted of the cost per phosphate bound daily and the cost per successfully controlled patient. Two break-even analyses were examined adjusting for the daily cost and percent of successfully controlled patients based on the most cost-effective agent. RESULTS: Lanthanum carbonate has a lower DACON (3.3) compared with sevelamer hydrochloride (8.2) and sevelamer carbonate (8.2) yet results in a greater amount of phosphate bound daily (514.8 mg versus 236.2 mg and 236.2 mg).  This translates into $0.03 per 1 gm of phosphate bound daily as compared to $0.07 for sevelamer hydrochloride and $0.06 sevelamer carbonate.  The daily cost of lanthanum carbonate would need to increase between 114-167% for the cost per phosphate bound to be equivalent to sevelamer carbonate or sevelamer hydrochloride.  The yearly cost per successful treatment was $7,542 with lanthanum carbonate, $17,476 with sevelamer hydrochloride, and $13,981 with sevelamer carbonate. The percent of successfully controlled patients treated with sevelamer carbonate or sevelamer hydrochloride would need to increase 85%-131% for the cost per successfully controlled patient to be equivalent to lanthanum carbonate. CONCLUSIONS: These results suggest lanthanum carbonate is a cost-effective phosphate binder in the treatment of hyperphosphatemia among CKD patients relative to other second line agents.