We present data on urinary oxalate (U(OX)), renal function, growth and bone age in a 10-year-old male with primary hyperoxaluria type 1. The patient had undergone combined liver-kidney transplantation at the age of 4.5 years. UOX increased up to 10(4) micromol/24 h after transplantation and declined to normal values thereafter. Excessive Uox concentrations after surgery might have been due to a bone pool of unsoluble oxalate and declined spontaneously. Creatinine clearance remained stable during observation period. The boy showed significant catch up growth. Height standard deviation score for chronological age improved from -2.4 before transplantation to -0.3 after 6 years. Radiological bone density improved at the same time. Hepatorenal transplantation should be performed in children with primary hyperoxaluria 1 before end-stage renal failure to normalize oxalate excretion and improve growth and bone mineralization.