The infantile form of primary hyperoxaluria is a very rare disease and often presents as a lifethreatening condition because of rapid progression to end-stage renal disease and systemic oxalosis. We described two infants with primary hyperoxaluria type 1 (PH1). Persistent severe hyponatremia and hypoalbuminemia were noted in both patients and cerebral and pulmonary involvements of systemic oxalosis were suspected in one patient. Such a severe phenotype of infantile PH1 is an important fi nding that should be added to the list of manifestations of PH1.