The greatest challenge for the treatment of children with cancer is to attain the highest probability of cure with the least morbidity. This has stimulated advances in radiotherapy technology. In recent literature published regarding proton radiation therapy (PRT) for pediatric cancer patients, PRT has been shown to have a distinct advantage over conventional photon therapy because of the ability to confine the high-dose treatment area to the tumor volume and minimize the radiation dose to the surrounding tissue. This is particularly important in children, in whom late effects of radiation to normal tissue can include developmental delay and increased risk of second malignant neoplasms. Several proton facilities are operating world-wide, and several medical centers in the United States and Europe are in the midst of planning and constructing new proton facilities. This may enlarge the role of radiation therapy in the multimodal management of children with cancer.