Lithium carbonate is a widely prescribed and effective psychotropic drug which, unfortunately, has a low therapeutic index and important acute and chronic toxicity (1). In particular, acute lithium poisoning, due to deliberate or accidental overdosage, can be fatal or lead to permanent neurologic sequelae. The management of acute lithium intoxication includes cardiorespiratory support, seizure control, and drug elimination enhancement. Increased elimination may be achieved with forced saline diuresis. At lithium concentrations ≥3.5 to 4 mmol/L, saline diuresis may be inadequate and hemodialysis (sometimes prolonged and repeated) is considered the treatment of choice. Lack of hemodialysis facilities may delay appropriate therapy. Continuous arterio-venous hemodiafiltration is a dialytic therapy increasingly used in critically ill patients (2). We report its effective use in increasing lithium clearance in a patient with acute lithium poisoning. Continuous arterio-venous hemodiafiltration can be rapidly instituted in a critical care environment without the need for specialized staff or facilities, and could replace the use of conventional hemodialysis in acute lithium intoxication.