Previous studies have suggested an association between parental medical radiation exposure and increased incidence of certain childhood cancers. We investigated the relationship between medical radiation and risk of neuroblastoma in offspring using data from a North American case-control study. Cases were children diagnosed with neuroblastoma from 1 May 1992, to 30 April 1994, at Children's Cancer Group and Pediatric Oncology Group institutions throughout the United States and Canada. One matched control per case was selected using random-digit dialling. Telephone interviews were conducted with parents to collect data on any medical radiation examinations and treatments in the 2 years before conception or during pregnancy. We included 500 maternal and 339 paternal matched pairs. Overall, no association was found between maternal exposure to radiation and neuroblastoma risk (odds ratio [OR] = 1.0; 95% confidence interval [CI]: 0.7, 1.3). Analysis of maternal exposure by specific anatomical site showed no association for gonadal sites [OR = 1.0; 95% CI = 0.5, 2.0]. Little association was found with paternal radiation exposure [OR = 1.2; 95% CI = 0.8, 1.81. No consistent exposure-response gradient was found based upon the number of maternal or paternal medical radiation examinations. The data presented here, coupled with the lower radiation doses currently used, indicate that any further study of this question will require larger studies with improved exposure assessment.