Eighty-five cases of pediatric non-Hodgkin's lymphomas (NHLs) from Mexico have been reviewed and classified according to histologic type and immunophenotype using a panel of markers which included CD20, CD45RO-(UCHLI), CD3 and Tdt. Twenty-five cases were classified as lymphoblastic lymphoma (LBL) of precursor cell origin and forty-nine cases as non-lymphoblastic lymphomas. Eleven cases could not be satisfactorily classified due to insufficient tissue or on technical grounds. All these lymphomas were subjected to immunohistochemistry (IHC) for detecting p53 expression. p53 was detectable in 7 (28%) lymphoblastic lymphomas, in 36 (73.4%) non-lymphoblastic lymphomas and in 4 (36.3%) of the lymphomas that could not be classified. Our results indicate that in contrast to adults with NHL and children with acute leukemia, p53 expression is relatively frequent in pediatric NHLs, although it is higher in lymphomas of B cell phenotype than in those of T cell type.