The number of children who undergo cardiac, renal, and liver transplantation continues to increase. This review of the literature describing their cognitive function indicates that deficits ranging from gross IQ delay to subtle neuropsychological dysfunction are present in some of these children both before and after transplantation. However, with the exception of certain definite contributors to vulnerability, such as cyanotic heart disease, early onset of disease, and growth deficits in infancy (particularly in head circumference and height), the correlates of cognitive deficits are not clear. Problems with determining contributing variables include significant heterogeneity within study populations, difficulties obtaining appropriate control groups, and the need for longitudinal, long-term studies. Additional research is required to address limitations of past studies.