OBJECTIVES: Real-world data may inform decisions regarding treatment for renal cell carcinoma (RCC). We compared treatment persistence and healthcare costs for sunitinib and pazopanib, considering dosing cycle differences' effect on days supply. METHODS: This retrospective cohort study used the Truven Marketscan® database. Inclusion criteria were RCC diagnoses, age ≥ 20 years, ≥1 (index) prescription for sunitinib or pazopanib 10/1/2009 – 9/30/2013, and continuous plan enrollment ≥6 months before to 12 months after index. We compared demographic and clinical characteristics and treatment patterns, using Chi-square, Student t-test, and Wilcoxon signed-rank test (α=0.05). Costs were compared using generalized linear modeling to adjust for demographic, clinical, and medication variables. Sensitivity analysis assessed effects of imputing days supply for sunitinib’s 42-day dosing for prescriptions with 28 or 30 days supply. RESULTS: Among 466 patients (77% receiving sunitinib), the cohorts were not significantly (NS) different in demographics or Charlson Comorbidity Index. More sunitinib patients (46 vs. 6 pazopanib patients; p=0.038) had chronic pulmonary disease. The sunitinib cohort had less time between diagnosis and index prescription than the pazopanib cohort (334 vs. 422 days; p=0.037). Proportions of patients with treatment continuation, discontinuation, switching, or interruption were NS different. Before imputation, adjusted mean [SD] daily medication costs during persistence were higher for sunitinib ($218.19 [34.73] vs. $177.07 [45.76]; p<0.0001), but NS different after imputation (sunitinib $181.41 [22.34] vs. pazopanib $175.77 [44.26]; p=0.213). Twelve-month adjusted RCC-related medical costs were significantly lower for sunitinib than pazopanib before imputation ($36,638.96 [$25,199.38] vs. $45,219.75 [$34,828.70], p=0.021) and after imputation ($36.393.90 [$26,543.89] vs. $45,652.99 [$35,226.83], p=0.015. The RCC-related prescription costs were NS different between the two drugs before and after imputation. CONCLUSIONS: Treatment patterns and persistence with sunitinib or pazopanib were NS different. Sunitinib daily cost was NS different from pazopanib after imputation. Further analysis is needed regarding dosing schedule, days supply, and related calculations.