The progressive encephalopathy observed in 5 children with chronic renal failure was clinically similar to the so-called dialysis encephalopathy of adults, except that it was not related to dialysis therapy. Renal osteodystrophy is more prevalent in children than in adults and often more severe. The attempt to control the crippling deformities of renal osteodystrophy in growing children with renal insufficiency has led to the use of large quantities of aluminum containing antacids. The encephalopathy observed in children with chronic renal failure may be related to the oral ingestion of aluminum containing compounds in the presence of persistent secondary hyperparathyroidism. We suggest that alternative methods for the adequate control of serum phosphorus levels should be sought and indications for parathyroidectomy in children reevaluated. During the past 18 mos we have lowered the dose of aluminum containing compounds to 50 to 100 mg/Kg/day in our patients with progressive renal failure and recommend parathyroidectomy. No new cases of the encephalopathy have occurred.