Preemptive isolated liver transplantation (PLTX) can cure the metabolic defect in primary hyperoxaluria type 1 (PH1) but there are no uniformally accepted recommendations concerning the timing of this transplantation procedure. We have performed PLTX successfully in 4 children (age 3-9 years) with PH1 with no mortality or morbidity due to the transplantation procedure. Plasma and urinary oxalate levels normalised rapidly and renal function remained stable including one patient with advanced chronic renal failure who showed a stable course for more than 24 months. Although treatment must be individualised in this severe metabolic disorder and PLTX has to be viewed as invasive procedure, we feel PLTX should be offered and discussed not too late in the treatment of PH1 to prevent or at least delay the progression to end stage renal disease and systemic oxalosis.