PURPOSE: To evaluate the patient costs for imaging and compliance with imaging protocols in pediatric patients in the National Wilms Tumor Study (NWTS) IV. MATERIALS AND METHODS: The medical and imaging records of 60 patients (28 male, 32 female; aged 3 days to 12.6 years) in NWTS IV were reviewed. Initial imaging and follow-up imaging were evaluated separately. Three levels of follow-up compliance were evaluated. RESULTS: The total patient cost for imaging was $442,180: $94,212 for initial and $347,968 for follow-up studies. Many areas of potential cost savings were identified. Protocol compliance was variable. Seventy-five percent of patients underwent studies in full compliance with the initial protocol requirements. For follow-up, compliance was 0%-80% for different studies at different compliance levels. For no study was compliance 100%. CONCLUSION: Imaging costs in pediatric patients with Wilms tumor are substantial. Protocol compliance was not optimal.