Continuous hemofiltration was first described as a new form of renal replacement for critically ill patients in the late 1970s. Since then, it has undergone remarkable technical and conceptual modifications and has become a widely used form of dialytic therapy in the ICU. More recent insights into the pathogenesis of sepsis and the role of soluble molecules in the mediation of organ injury during septic shock have led to a resurgence of the concept of blood purification during life-threatening infection. Recent studies have confirmed that cytokine extraction occurs in vivo in humans during continuous hemofiltration and that other smaller, potentially noxious molecules such as platelet-activating factor, complement factors C5a and C3a, and thromboxane are also removed from the circulation of septic patients or animals. Experimental studies have shown that continuous hemofiltration has beneficial hemodynamic effects in septic animals and that such effects may correlate with the intensity of ultrafiltration. Cardiac function also appears to improve and myocardial depressant factors are removed from the circulation. Continuous hemofiltration offers some promise as an adjunctive form of treatment in severe sepsis.