Cancer is the second most common cause of death among children aged 0–14 years, surpassed only by accidents. Of all childhood cancers, the malignant lymphomas [Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL)] rank third in incidence.FDG PET/CT performed with enhanced or non-enhanced CT has been shown to be more accurate than CECT for evaluation of disease extent and treatment response by providing metabolic information in patients with aggressive lymphoma. In addition, the standardized uptake value (SUV), a semi-quantitative index, is helpful for determining diseaseaggressiveness, for objective treatment response assessment and for outcome prediction.Whole-body MRI and whole-body DWI in particular, provides a radiation-free alternative for staging malignant lymphoma in children.The review of this context consists of chapters about lymphoma in pediatrics, PET/CT role of lymphoma, physics of diffusion, and role of Diffusion MR in lymph nodes.This study was performed upon 20 patients underwent whole body diffusion MR with PET/Ct used as reference standard, and shows that whole body MR diffusion may play an important role complementary to the PET/CT in initial staging and evaluation of pediatric HD patients after chemotherapy, however we still in need to more further studies to prove this fact.