Paraquat can be removed by haemodialysis and haemoperfusion but, although clearance values are high, the quantities recovered are insignificant. Prevention of death is most unlikely except perhaps in patients with plasma paraquat concentrations very close to the previously proposed line separating concentrations in fatal cases and survivors at different time intervals. Even if delays incurred in measuring plasma paraquat concentrations and in setting up haemodialysis or haemoperfusion could be reduced to a minimum, elimination by these procedures would achieve little because paraquat disappears rapidly from the plasma in the first few hours after ingestion as it is taken up by the tissues and excreted into the urine. Further studies on patients at borderline risk are required and the value of 'continuous' haemoperfusion requires further assessment.