There were 150 children with neuroblastoma and 183 children with Wilms' tumor who received radiation therapy, orthovoltage up to 1967, and cobalt therapy thereafter. In all except two cases, radiation therapy crossed the midline. Of all of the children treated, 13 required spinal fusion. There were six with Wilms' tumor; three had kyphosis; and three had scoliosis. Nine fusions were done with three pseudoarthroses, one broken rod, and two hook pullouts. There were seven with neuroblastoma, of whom five had kyphosis and two had scoliosis. Nineteen spinal fusions were done on these seven patients for neuroblastoma; two developed paraplegia; seven had pseudoarthroses; two had broken rods; and one had infection. Complications were attributed to laminectomies (five of seven) and high orthovoltage dosage (3680 rad), causing bone death and destroyed bone growth, with resultant infantile-size spines. The authors continue to follow up postradiation patients and observe rapid deterioration of kyphosis and scoliosis during the adolescent growth spurt. The authors now recommend early and extensive combined two-stage, long anterior and posterior fusions for kyphosis of 35 degrees and over, and a posterior fusion with Harrington rod instrumentation with extensive bone grafting is done for early (35 degrees) pure scoliosis. Postoperative immobilization is much longer than for regular spine fusions--at least one year.