The last decade has provided extensive knowledge of the molecular mechanisms of lymphomagenesis. Disruption of programmed cell death is a key feature of many low-grade lymphomas, while more aggressive lymphoid tumors carry additional genetic alterations, e.g. in the molecular pathways that control the cell division cycle and DNA repair. The application of genetic analysis and gene expression profiling of lymphoid tumors may be used as diagnostic and prognostic tools, and may help identifying new targets for specific, biologically based treatment strategies, which can supplement or replace the conventional chemotherapy.