Sustained low-efficiency dialysis (SLED) is an increasingly popular extracorporeal renal replacement therapy for patients with renal failure in the intensive care unit (ICU). Several centers across the world employ this 'hybrid' technique, which has advantages of both intermittent and continuous methods. The goal of these centers is to provide an easy-to-perform treatment with reduced solute clearances for prolonged periods. Many centers use standard, sophisticated dialysis equipment for SLED. An increasing number of hospitals in Europe and South America employ a single-pass batch dialysis system, the procedural simplicity of which makes it an ideal modality for SLED in the ICU. All systems offer the advantages of flexible timing of treatment and reduced costs; their ease of handling means that SLED is readily accepted by ICU staff. Prospective controlled studies have shown that SLED clears small solutes with an efficacy comparable to that of intermittent hemodialysis and continuous venovenous hemofiltration (even when the latter employs high rates of fluid substitution). Cardiovascular tolerability associated with SLED is similar to that associated with continuous renal replacement therapy, even in severely ill patients. Nocturnal dialysis -- a special form of SLED -- has all the advantages outlined above, with the added benefit of unrestricted physician access to the patient during the day, minimizing the interference of renal replacement therapy with other ICU activities.