Fifty-eight cases diagnosed as malignant lymphoma in patients younger than 15 years between 1976 and 1986 in the Kanto area were reviewed and reclassified as follow: 48 non-Hodgkin's lymphomas, 9 Hodgkin's disease and one malignant histiocytosis. Lymphoblastic type consisted of 26 cases or 54.2%; large cell type, 11 cases or 22.9%; Burkitt's type, 7 cases or 14.5%; medium-sized cell type and mixed cell type consisted of 4 cases. There was no follicular lymphoma case. A rare sclerosing mediastinal lymphoblastic lymphoma and diffuse large cell lymphomas with T-zone involvement as well as primary epidural Burkitt's lymphomas were found. Immunohistochemical studies using paraffin sections were performed in 43 non-Hodgkin's lymphomas and phenotypes of 37 cases were determined as follows; T cell origin in 24, B cell origin in 11 and non-T non-B in 2 cases. Of 25 lymphoblastic lymphomas, LCA was positive only in 11 cases. Reed-Sternberg cells and their variants of Hodgkin's disease reacted with anti-Leu M1 antibody in 3 of 8 examined but not with EMA antibody. This study revealed that the survival was related to sites of the primary lesion, regardless of histological type and immunologic phenotypes.