This study evaluates the importance of magnetic resonance imaging (MR) in the exploration of the abdomen in a case of non-Hodgkin lymphoma diagnosed in a 14-year-old boy. Results are compared with those obtained using two widely used diagnostic methods: CT and ultrasonography (US). US revealed a prevalent involvement of the spleen, whereas CT showed a marked hepatic infiltration. The role of MR seems important because it allowed the contemporary and careful evaluation of hepatolienal involvement. The main advantages and drawbacks of using MR in pediatrics, and in particular in the study of the metastatic involvement of hypochondriac organs are discussed.