Introduction Ferritin is regarded as prognostic marker for various cancer diseases. We investigated ferritin change over time rather than cross sectional value of ferritin concentration in the prognostic value in childhood cancer patients and survivors. Method The patients with cancer who were diagnosed and treated in Yonsei Cancer Center were reviewed retrospectively. Ferritin concentration was tested from Jan 2013 to June 2017. Minimum and maximum ferritin concentration (Minferr and Maxferr) and tested date were obtained. The area under the curve (AUC)of ferritin was calculated from the plot of ferritin concentration and tested dates. The calculated AUC was expressed as ‘ferritin product(FerrPro)’. Receiver operating characteristic analysis applied for the any cause of deaths of patients and prognosis role of ferritin. Result Total 941 patients were enrolled. Leukemia was 257 (27.3%), brain tumor (132, 14.0%), abdomen tumors (119, 12.6%), lymphoma (91, 9.7%) and others. They were diagnosed as disease from 1973 to 2017. In total group, AUC for FerrPro was 0.888, MaxFerr was 0.880 and MinFerr was 0.831. In the group of ferritin tested within 100days from diagnosis, AUC of FerrPro was 0.863, MinFerr was 0.861, and MaxFerr was 0.831. In group of ferritin tested after 100days after diagnosis, AUC of FerrPro was 0.899, MinFerr was 0.811 and MaxFerr was 0.906. FerrPro level of 700 was highly prognostic for overall survival in ferritin tested 100 days group( P0.001). All diagnosed showed trend for prognosis value of FerrPro, but patient with abdomen tumors showed statistical significant survival difference by FerrPro700 ( P=0.003). Conclusion FerrPro showed prognostic implications for childhood cancer patients, when test was started early after diagnosis and repeatedly tested over time. Min and MaxPro also had implications according to the test settings.