The body of this work illustrates the utility of the combined cytogenetic and molecular approach to lymphoid tumorigenesis. A number of tumor-specific translocations have proven amenable to dissection by molecular techniques. We have a firm grasp of the general principles that underlie lymphoid neoplasia; in particular, the activation of cellular oncogenes by translocation into genes of the immunoglobulin superfamily is a widespread phenomenon. However, numerous lymphopoietic malignancies are only poorly understood. These remain a challenge for the continued application of these methodologies.