Inhibition of interleukin 6 (IL-6) signalling has been proposed as a potential cardioprotective strategy for patients with chronic kidney disease (CKD) but the direct renal effects of IL-6 inhibition are not established. A Mendelian randomization (MR) study was performed to investigate the association of genetically proxied inhibition of IL-6 signalling with estimated glomerular filtration rate (eGFR), CKD and blood urea nitrogen (BUN). Inverse variance weighted MR was used as the main analysis, with sensitivity analyses performed using simple median, weighted median and MR-Egger methods. There was no evidence for an association of genetically proxied inhibition of IL-6 signalling (scaled per unit decrease in natural log transformed C-reactive protein) with log eGFR (0.002, 95% confidence interval -0.004 – 0.008), BUN (0.088, 95% confidence interval -0.003 – 0.019) and CKD (odds ratio 1.018, 95% confidence interval 0.899 – 1.153). These findings suggest that inhibition of IL-6 signalling is unlikely to have a direct effect on renal function.