All cases of persistent renal failure in infants less than 1 year of age were reviewed to determine whether the prognosis has improved equally for infants as for adults. During a ten-year period, 52 infants were treated by applying uniform therapy; 28, more than half, were less than 4 weeks old. All cases were separated into two groups: 19 infants without and 33 infants with congenital renal or urinary tract anomalies. In 20 patients of the latter group, additional serious anomalies of other organs were present. The age distribution was strikingly different: in 18 of 21 infants, renal anomalies were present, as diagnosed on the first day of life. In contrast, only 3 of 11 infants, 4 to 12 months old, had urinary tract anomalies. In infants without renal anomalies, renal failure was caused by hypotension or shock in 10 of 19 cases, by pyelonephritis or sepsis in 6 of 19. Of this group, eight infants (42%) recovered completely, nine (47%) died. Death occurred within one to two days of hospitalization in all but three cases, caused by shock or sepsis. In this group medical problems that are amenable to therapy have caused either renal failure or contributed to the infant's death. In infants with renal or urinary tract anomalies, renal failure was caused by renal dysplasia or agenesis in 16 of 33 infants, by urinary tract obstruction in 12 of 33. Only three patients (9%) recovered, all older than 4 months, 20 (61%) died, and 10 are living with signs of chronic renal failure. Death usually occurred within one week of hospitalization and, in 16 of 20, it was caused by renal failure and multiple additional anomalies. The multiplicity and complexity of the congenital anomalies in most instances precluded effective, lifesaving therapy. Renal failure in infants is still a serious disease accompanied by a high mortality rate in which therapeutic possibilities are limited. No improvement in prognosis can be expected in the near future.