Reversal of cardiac dysfunction secondary to type 1 primary hyperoxaluria after combined liver-kidney transplantation. A 23-year-old man with type 1 primary hyperoxaluria, renal failure, and oxalosis developed a severe cardiomyopathy while awaiting combined liver-kidney transplantation. This manifested as radiographic cardiomegaly, a dilated hypokinetic left ventricle with a decreased ejection fraction, ventricular arrhythmias, and cardiac uptake on bone scanning. On liver and kidney transplantation, these abnormalities markedly improved and/or reversed. The cardiac size almost normalized, the left ventricular ejection fraction increased from 20% to 34%, the ventricular arrhythmias resolved, and the cardiac uptake on bone scanning disappeared. This coincided with normalization of oxalate production and excretion. Severe cardiac involvement secondary to oxalosis in patients with primary hyperoxaluria may improve or reverse with combined liver-kidney transplantation. 