We studied the psychological and emotional problems experienced by seven children and their families who underwent bone marrow transplantation at the University of Colorado Medical Center from 1973 to 1975. These problems included (1) anxiety and depression relating to isolation, fear of death, and painful procedures; (2) an overdependence associated with a feeling of helplessness; (3) anger directed toward both the staff and the parents; (4) a reduced tolerance for medical procedures; and (5) periodic refusal to cooperate. Initially we had been concerned that patients might become agitated, psychotic, or even suicidal. These did not occur. Severe anxiety over bodily changes was not a problem. We did not encounter prolonged refusal to cooperate, refusal to remain in isolation, or drug addiction. Important aspects in management included an honest, straightforward, and direct discussion of all aspects of transplantation, including the potential complications and the risks of death from the underlying disease or from complications of transplantation. A firm but understanding approach to the patients appeared to be the most effective method to develop their continuing cooperation. The opportunity for patients to express verbally their fears of procedures and of death was essential. The donors needed help in working through their feelings of guilt if a transplant was not successful. The parents needed continuing psychological support for the many personal, social, and psychological difficulties which they had to face.