Acute kidney injury in the ICU is increasing dramatically worldwide, making the need for renal replacement therapy (RRT) greater than ever. Unresolved issues are questions like when do we start RRT and how do we measure its dose. Several recent trials could show that the relationship between dose of RRT and survival is not a linear one, leaving it to the discretion of the nephrologist and/or intensivist to choose the mean of RRT and its dose in a complex therapeutic concept for the critically ill patient. Highly efficient means of RRT eliminate potentially life-saving drugs like antibiotics to a larger extent than one or two decades ago. As sepsis is responsible for the onset of acute renal failure in more than half of the patients careful adjustment (i. e. increase) of the dose of antibiotics is crucial to avoid under-dosing of these drugs. This holds also true for the nutritional support of these patients as increasing the dose of renal replacement therapy also enhances the elimination of nutrients.