FK506-induced leukoencephalopathy is a well-known entity in adult organ transplant patients. The neurotoxicity of FK506 immunosuppression is frequently reversible, with either reduction or cessation of the drug. This neurologic syndrome is not well documented in children. We report the clinical and radiologic features in four pediatric cases of FK506 leukoencephalopathy. In two of the four patients this syndrome was reversible.