Low-grade inflammation is a common feature of chronic kidney disease (CKD) already before the start of renal replacement therapy, and evidence suggests that persistent inflammation may also be per se a risk factor for progression of CKD and vascular disease. Many factors, including retention of pro-inflammatory cytokines, advanced glycation end products, reactive oxygen species, autonomic dysfunctions and volume overload may contribute to inflammation when renal function declines. The aim of the present review is to summarize the causes and consequences of a chronic inflammatory state in the CKD population before start of renal replacement therapy, with special emphasis in polymorphnuclear leukocyte priming, which may be a key mediator in the induction of a vicious circle of oxidative stress and inflammation in CKD. A more thorough characterization of uremic retention solutes with regard to their specific pro-and anti-inflammatory properties is needed.