In a case of acute intoxication with high-dose methotrexate, a kinetic study of plasma methotrexate concentrations enabled the authors to begin treatment with high-permeability membrane haemodialysis combined with intensive folic acid loading before the clinical signs of iatrogenic toxicities developed, and to continue with haemodialysis rather than using other depurative methods. In this case, the post-depuration course was favourable: dermatological signs and febrile pancytopenia regressed within 4 days, and these was no sign of hepatic toxicity.