OBJECTIVES: Burkitt's lymphoma (BL) is a highly aggressive mature B-cell neoplasm comprising endemic, sporadic and immunodeficiency-associated variants. Human cell lines constitute a very useful tool to investigate the biology of lymphoid neoplasia. In this study, we succeeded in establishing two human cell lines, GAL-01 and GAL-02, from a HIV-negative patient with Epstein-Barr virus (EBV) -negative sporadic BL presenting as an effusion. GAL-01 and GAL-02 were established at diagnosis and after one course of polychemotherapy, respectively. The in vivo effusion occurred in a very peculiar clinical setting; the patient having a previous history of intestinal diffuse large B-cell lymphoma. METHODS: The morphologic, immunophenotypic and molecular genetic features of GAL cell lines are reported and compared with those of the parental tumour. The findings clearly demonstrated that the Burkitt effusion did not represent disease progression of the intestinal tumour, but represented a second primary haematological malignancy. The in vivo tumorigenic properties of the cells were tested by subcutaneous injection to NOD/SCID mice. RESULTS: Both cell lines were composed of medium-sized lymphoid cells with clumped chromatin, multiple medium-sized nucleoli and moderate amounts of vacuolated cytoplasm. GAL cells display the phenotype and genotype of a B-cell lineage (positive for CD20, CD79a and clonal rearrangement of Ig heavy chain), carry the c-MYC rearrangement by t(8;22)(q24;q11) translocation and are characterised by the expression of the germinal centre-associated antigens CD10, BCL6, CD38 and absent to low BCL2 expression. EBV and HHV8 were not identified within parental tumour or in cultured cells. Subcutaneous injection of both cell lines to NOD/SCID mice induced tumour formation. CONCLUSIONS: GAL-01 and GAL-02, two novel EBV-negative human BL cell lines represent a potentially useful experimental model to study the biology of BL possibly including the resistance to chemotherapy.