Background: TKIs and statins alone can cause liver injury. When used together, there is additive risk for hepatotoxicity, as seen with pazopanib and simvastatin, and the potential for discontinuing TKI therapy.Liver enzyme abnormalities are also associated with mTORi.Hepatotoxicity from concurrent use of statins as a class with TKI or mTORi as a class in real world practice in mRCC has not been reported. Methods: This observational cohort study included adult patients treated with a TKI or mTORi for mRCC at the Huntsman Cancer Institute from 2004-2014. We performed a treatment line analysis. For each treatment line, CTCAE criteria were used to categorize maximum AST, ALT, and total bilirubin.Highest grade of any liver enzyme was compared between TKI with and without statin and between mTORi with and without statin (Fisher’s Exact test). Results: A total of 162 treatment lines were included. For TKI and statin, the three most common treatment line combinations were sunitinib and simvastatin (7), sunitinib and atorvastatin (4), and pazopanib and simvastatin (3). For mTORi and statin, the three most common treatment line combinations involved simvastatin with temsirolimus (7) and everolimus (3). Prevalence of hepatotoxicity is shown in the table. Conclusions: Our results show a trend toward significance in the prevalence of hepatotoxicity with concomitant mTORi and statin versus mTORi alone, perhaps explained by mTORi-mediated competitive inhibition of simvastatin (sensitive CYP 3A4 substrate). There was no difference in hepatotoxicity for TKI with or without statin, although there were few pazopanib and simvastatin combinations. Study limitations include the small sample size, limited number of TKI or mTORi and statin combinations, and retrospective study design. A larger study is needed to validate these findings.