Peripheral tissues, such as skin and muscles, are sensitive to alterations in perfusion. During circulatory shock, these tissues are the first to receive less blood and the last to recover after treatment. By monitoring peripheral circulation, disturbance of the systemic circulation can be detected at an early stage. Peripheral perfusion is often disturbed in critically ill patients. Peripheral perfusion may remain disturbed, even if conventional hemodynamic parameters such as blood pressure and heart frequency normalize after treatment. Persistent abnormal peripheral perfusion is related to a poorer clinical course. With current non-invasive methods, peripheral circulation in critically ill patients can easily be assessed at the bedside. Interventions that improve peripheral circulation may speed up recovery in critically ill patients.