Infection remains a major cause of morbidity and mortality in the dialysis patient. Most of these infections are bacterial and often lead to sepsis. In this review the possible influence of the biocompatibility of the dialysis membrane on the incidence of bacterial infections is discussed. Specifically, the role of the membrane on granulocyte function such as phagocytosis, adhesion, and production of reactive oxygen species is shown to be adversely affected by recurrent exposure to complement-activating membranes. Recent clinical studies also support the notion that dialysis with bioincompatible membranes is associated with a higher incidence of clinical infections than membranes that are more biocompatible.