Blood lactate levels are frequently measured in critically ill patients. Whilst these measurements are known to be accurate, for the correct interpretation of hyperlactataemia, it is essential to have sufficient understanding of anaerobic and aerobic mechanisms of production and clearance. The consistency of the prognostic value emphasizes the place of lactate measurement in the risk-stratification of critically ill patients. However, until recently the clinical benefit of lactate-guided resuscitation in critically ill patients was unknown. By referring to two recent multi-centre randomized controlled trials, this review provides an update on this important topic. The first study showed that lactate clearance was non-inferior to central venous oxygen saturation (ScvO2) as a goal of early resuscitation in patients with severe sepsis or septic shock who presented to the Emergency Department (ED). The second study showed that in patients with hyperlactataemia on ICU admission, lactate monitoring significantly reduced hospital mortality when adjusting for predefined risk factors, a finding that was consistent with important secondary endpoints. This suggests that lactate monitoring has clinical benefit and that lactate measurement should be incorporated in goal-directed therapy. © 2011, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.