Although several advantages have been attributed to continuous renal replacement therapy (CRRT), including greater hemodynamic stability permitting better fluid removal, improved recovery of renal function, and more efficient removal of small and large metabolites, none of these factors has been adequately corroborated in controlled trials. On the other hand, sustained low efficiency dialysis (SLED) has enjoyed an unsurpassed renaissance over the last decade for treatment of severely ill patients with acute kidney injury in the intensive care unit (ICU). SLED combines excellent detoxification and good cardiovascular tolerability for even severely ill patients in the ICU. SLED also provides good treatment time flexibility at lower costs than CRRT with the advantage that existing dialysis systems can be used. In conclusion, SLED represents an alternative to CRRT, enabling optimal treatment of complex critically ill patients. It can be considered a key treatment modality for patients on ICU, giving nephrologists and ICU physicians the opportunity for pooling their twin areas of expertise.