Two T-cell lymphomas induced by a combination of antigen stimulation and immunosuppression in inbred C57Bl/6J mice, BWL1 and BWL2 (Ryd et al. 1985), were further characterized. Cytogenetically they have the same trisomy 15 abnormality as chemically, virally and radiation induced T-cell lymphomas. Analyses of early and late tumour generations indicate that both tumours are chromosomally stable. After i.v. transplantation, the two tumors grew in a similar manner and preferentially in spleen and liver. Proteolytic treatment of the tumor cells changed the distribution of both lymphomas from the lungs to other organs. Neuraminidase treatment had no such effect on BWL2, but a similar but weaker effect than pronase on BWL1. Our findings support the notion that the distribution of lymphomas are, at least in part, governed by cell-surface characteristics.