An 18-year-old woman diagnosed with piridoxine-resistent primary hyperoxaluria type 1 (PH-1) and progressive renal insufficiency complicated with acute renal failure of obstructive origin who developed systemic oxalosis affecting the heart (cardiomyopathy), the skin (cutaneous ulcers) and vascular system (lower limb ischemia, as well as pulmonary and cerebral microcirculatory blockage resulting in pulmonary hemorrhage and tonic-clonic general seizures. As conventional hemodialysis (HD) or peritoneal dialysis (PD) are unable to eliminate enough oxalate to avoid a continuous positive balance, long daily sessions (6-7 h) of high-flux hemodialysis (highly permeable polyamide membrane of 2.1 m2) for 67 consecutive days normalized blood oxalate levels and reversed the systemic complications secondary to the calcium oxalate crystals deposit. The patient underwent a combined liver-kidney transplantation and has progressed well to the present time. The most important factors in PH-1 treatment are analyzed. Even though combined liver-kidney transplantation is the treatment of choice and should be performed before the glomerular filtrate rate (GFR) falls below 25 mL/min/1.73 m2, intensive HD becomes necessary to prevent oxalosis in the face of acute renal failure. Also, as our case shows, intensive HD can achieve a negative oxalate balance and reverse both the systemic lesions and the oxalate deposits.