Increased fecal bile acid loss and defective in vitro ileal bile acid uptake were demonstrated in an 8-year-old boy with diarrhea starting in the neonatal period. His continuously normal physical development and good nutritional status are in keeping with a well-preserved cholic acid pool and normal duodenal bile acid concentration. Isolated bile acid malabsorption can remain well compensated and present as the chronic nonspecific diarrhea syndrome of childhood.