Purpose: Earlier, the association of single nucleotide polymorphisms (SNPs) with toxicity and efficacy of sunitinib has been explored in patients with metastatic renal cell carcinoma (mRCC). Recently, additional SNPs have been suggested as potential biomarkers. We investigated these novel SNPs for association with sunitinib treatment outcome in mRCC patients. Methods: In this exploratory study, we selected SNPs in genes CYP3A4, NR1I2, POR, IL8, IL13, IL4-R, HIF1A and MET that might possibly be associated with sunitinib treatment outcome. Each SNP was tested for association with progression-free survival (PFS) and overall survival (OS) by Cox-regression analysis and for clinical response and toxicity using logistic regression. Results: We included 374 patients for toxicity analyses, of which 38 patients with non-clear cell renal cell cancer were excluded from efficacy analyses. The risk for hypertension was increased in the presence of the T allele in IL8 rs1126647 (OR = 1.69, 95 % CI = 1.07-2.67, P = 0.024). The T allele in IL13 rs1800925 was associated with an increase in the risk of leukopenia (OR = 6.76, 95 % CI = 1.35-33.9, P = 0.020) and increased prevalence of any toxicity > grade 2 (OR = 1.75, 95 % CI = 1.06-2.88, P = 0.028). No significant associations were found with PFS, OS or clinical response. Conclusions: We show that polymorphisms in IL8 rs1126647 and IL13 rs1800925 are associated with sunitinib-induced toxicities. Validation in an independent cohort is required.