OBJECTIVES:    The study’s aim is to assess the length of stay and costs by payer status of hospitalized patients with CDI and MRSA from 2009 to 2013. METHODS: Healthcare Cost and Utilization Project-National Inpatient Sample (HCUP-NIS) inpatient discharges from 2009 to 2013 were included. Cases were identified by ICD-9CM (CDI: 008.45; MRSA: 038.12, 041.12, 482.42). Primary expected payer status was categorized as Medicare, Medicaid and private insurance. Crude and adjusted linear regression analyses were performed. Age, race, number of diagnoses, Charlson comorbidity index, median household income and region were adjusted in adjusted model. RESULTS: After multi-variate adjustment, the rank of LOS among CDI and MRSA inpatients was consistent in 2009-2011: the rank of LOS in MRSA inpatient was: Private insurance (least) –Medicare-Medicaid (most) (2011, Δ(Medicare-Private)=-1.36 days, Δ(Medicare-Medicaid)=-2.05 days, p<.0001), while the rank in CDI inpatient is: Medicare (least) – Private insurance -Medicaid (most)(2011, Δ(Medicare-Private)=-1.41 days, Δ(Medicare-Medicaid)=-3.74 days, p<.0001); The rank of cost among CDI inpatients was: Medicare (least) – Private insurance -Medicaid (most) (2011, Δ(Medicare-Private)=-$5606.68, Δ(Medicare-Medicaid)=-7472.2,p<.0001) and Medicare (least) –Medicaid- Private Insurance (most) for MRSA (2011, Δ(Medicare-Private)=-$5414.9, Δ(Medicare-Medicaid)=-$5205.9, p<.0001). However, the rank changed in 2012 in multi-variate adjusted model. There was no statistical difference of cost and LOS three primary payers for CDI inpatient from 2012 to 2013 (2013, LOS: Δ(Medicare-Private)=-1.06 days, p=0.58, Δ(Medicare-Medicaid)=1.94 days, p=0.28; Cost: Δ(Medicare-Private)=-2892, p=0.33, Δ(Medicare-Medicaid)=6232, p<.0001). MRSA inpatients with Medicare had the longest LOS and highest cost compared with the other two, but the result was insignificant. (2013, LOS: Δ(Medicare-Private)=2.61 days, p=0.004, Δ(Medicare-Medicaid)=0.64 days, p=0.82; Cost: Δ(Medicare-Private)=-638.59, p=0.88, Δ(Medicare-Medicaid)=-3855.18, p=0.55). CONCLUSIONS: From 2009 to 2011, CDI and MRSA hospitalized patients with Medicare cost less and had shorter LOS than those with Medicaid and private insurance after adjustment. However, the trend inverted in 2012.  It is unclear if the result can be attributed to payment policy changes.