Renal epithelial function is the cornerstone of key excretory processes performed by our kidneys. Most of these tasks need to be tightly controlled to keep our internal environment in balance. Recently, the mTOR signalling network emerged as a key pathway controlling renal epithelial cells from the glomerular tuft along the entire nephron. Both mTOR complexes, mTORC1 and mTORC2, regulate such diverse processes as glomerular filtration and the fine tuning of tubular electrolyte balance. Most importantly, dysregulation of mTOR signalling contributes to prevalent kidney diseases like diabetic nephropathy and cystic kidney disease. The following review shall summarize our current knowledge of the renal epithelial mTOR signalling system under physiological and pathophysiological conditions.