Studies on the growth and development of patients with Bartter’s syndrome indicate that severe growth retardation occurs during infancy and early childhood. Delayed adolescent growth spurt has occurred in all patients studied thus far who had manifested the syndrome during infancy. Normal stature is eventually attained. Mental development ranges from normal to brain damage and dysfunction; however, the majority of patients show some degree of mental retardation. The coexistence of Leigh’s encephalopathy with Bartter’s syndrome in one patient and the finding of severe motor and cognitive retardation with communicating hydrocephalus in another indicate that the prognosis of mental development in some cases of Bartter’s syndrome is guarded. Particular attention should be given to maintaining normal nutritional status in all patients, particularly during infancy and early childhood.