This meta-analysis on 10 prospective RCTs, including 1193 patients after major surgery (cardiac surgery in 84% of patients), could not demonstrate a benefit for the use of N-acetylcysteine (NAC). Current evidence does not support the use of NAC in patients undergoing cardiac surgery. In animal experiments, NAC has attenuated ischemic renal injury. In addition, NAC may be of benefit in prevention of contrast-induced acute kidney injury (AKI). The exact mechanism of the renal-protective properties of NAC are unclear. Proposed mechanisms include scavenging properties, and regulation of nitric oxide (NO). In this meta-analysis, the authors evaluated the effects of NAC in a population of patients who underwent major surgery. Patients with sepsis or patients who were administered radiocontrast were excluded. A few aspects of the meta-analysis need to be highlighted. Firstly, over 80% of the included patients were patients who underwent cardiac surgery. A sensitivity analysis in the cardiac surgery patients rendered the same results. Therefore, the results of this meta-analysis are mainly applicable to the use of NAC after cardiac surgery. Secondly, the incidence of AKI with need for renal replacement therapy, probably the most relevant endpoint, was very low -- 2.9% in the NAC-treated patients and 2.4% in the control patients. A study should include 2 x 13,800 patients in order to detect a 20% relative risk reduction in a cohort with a baseline incidence of 2.5%. This could mean that this meta-analysis lacks power to detect differences for this end point. Thirdly, in the subgroup of patients with chronic kidney disease, there was a trend in the NAC group for less patients with a greater than 25% increase of serum creatinine. This may be of interest, but again the study lacks power to draw meaningful conclusions. Finally, a potential adverse effect of NAC is its anticoagulant properties. Although, coagulation was not studied, surrogate markers for this such as re-exploration or blood transfusion were not different between NAC and control patients. In summary, NAC does not have important renal protective effects after cardiac surgery.