OBJECTIVES: Hyperphosphatemia, an electrolyte disorder characterized by elevated levels of phosphate in the blood, is a risk factor for chronic kidney disease (CKD) and associated with increased risk of mortality. In addition to dietary changes phosphate binders (PB) may be administered to hyperphosphatemia patients to reduce phosphate levels.  The objective of this study is to evaluate the impact of PB on CKD patients with hyperphosphatemia. METHODS: A retrospective, cross-sectional analysis was conducted on 70,728 inpatient discharges in the MedAssets health system data diagnosed with CKD and hyperphosphatemia for 2009 through 2013. Cohorts of patients with and without PB were matched on age, sex, principal diagnosis, hospital bed size, region, and teaching status using a propensity score and Greedy matching algorithm. In-hospital mortality and length of stay (LOS) were compared between cohorts using multivariate logistic and negative binomial regression models, respectively, controlling for Deyo-Charlson comorbidity score, complications, and procedures. RESULTS: Of patients diagnosed with hyperphosphatemia approximately 46% were administered PB during their stay.  Matching resulted in 11432 patients in each cohort with a mean age of 61 and proportionately more males (54%) than females (46%).  Patients receiving PB had higher Deyo-Charlson scores (5.70 vs. 5.46, p<.0001) and higher rates of end-stage renal disease (74.6% vs 44.1%, p<.0001) and hemodialysis (65.4% vs 35.4%, p<.0001).  Patients without PB had higher rates of acute kidney failure (48.0% vs 33.7%, p<.0001) and transplants (6.8% vs 2.0%, p<.0001).  After adjusting for complications and comorbidities phosphate binder use was associated with 7.7% more inpatient days (IRR = 1.077, p<.0001) and a 28% mortality reduction (OR=0.718, p<.0001). CONCLUSIONS: After controlling for other variables, CKD patients with hyperphosphatemia receiving PB had lower risk of in-hospital mortality and longer LOS compared to patients without a PB.  Further studies should assess post-hospitalization outcomes as well as variation among types of PB.