Post-transplant lymphoproliferative disease (PTLD) biopsy material is rarely available in adequate quantity for research. Therefore, the present study was designed to expand biopsy material in scid mice. Epstein-Barr virus (EBV)+ve PTLD samples from five transplant patients were established in scid mice. PCR analysis of immunoglobulin gene rearrangements demonstrated that four of the five biopsies (80%) gave rise to scid tumours which represented the original tumour cell clones. Immunophenotyping showed that these four biopsies (and all scid tumours) expressed all EBV latent genes and a B lymphoblast phenotype; <or=26% T cells were found in the biopsy material whereas scid tumours showed a paucity of T lymphocytes. RT-PCR analysis revealed expression of IL-2, -4, -6, -10 and IFN-gamma in all tumour material, suggesting key roles for these factors in tumour growth. The results show that EBV+ve PTLD material can be expanded in scid mice giving rise to quantities of homogeneous malignant tissue sufficient for research studies.