Two cases of severe salicylate poisoning with maximal plasma levels of 6.9 and 8.9 mmol/l are described. In addition to supportive treatment and forced alkaline diuresis, one case was treated with haemoperfusion and the other with haemodialysis. The use of the same blood pump and blood flow allowed us to compare directly the effect of these methods in removing salicylate. There was a non-significant higher dialysance (mean 86 ml/min, s.d. +/- 8) than haemoperfusion clearance (mean 81 ml/min s.d. +/- 17) at a blood flow of 200 ml/min. As haemodialysis offers the theoretical advantage of correcting acid-base and electrolyte disturbances, does not trap platelets and has a lower heparin requirement, the present comparison indicates that haemodialysis is preferable when extracorporal elimination is indicated in salicylate poisoning.