Aluminium toxicity occurred in two infants with congenital uraemia who had never received phosphate binders or other aluminium-containing agents or intravenous fluids. One patient was treated by peritoneal dialysis from the age of two weeks and died at three months after the sudden onset of neurological symptoms; the other died after one month of conservative management without dialysis. Brain aluminium concentration was high in both infants (6.4 and 47 micrograms/g, respectively) whereas bone aluminium content was normal and there were no histological changes or stainable aluminium on bone biopsy specimens. Both infants were fed with 'Similac PM 60/40'. To investigate possible sources of aluminium, powdered milk formula, sterilised water used for preparation of the feed, and dialysate concentrate (first patient) were analysed. Aluminium concentration was high (232 +/- 60 ng/ml) in powdered milk but negligible in sterilised water and dialysate concentrate (4 ng/ml and 3.4 +/- 2.4 ng/ml, respectively). These findings indicate that proprietary infant milk formula is another source of aluminium. Aluminium-free milk should contribute to the prevention of aluminium toxicity in infants with renal failure.