Abstract Genome research lead to one of the largest scientific achievements of the last decade. Apart from sequencing the human genome, there was also a huge increase of knowledge regarding genomic aberrations in cancer. In Non-Hodgkin’s lymphomas (NHL), some of these findings already are of clinical relevance; specific genomic aberrations are characteristic of distinct subtypes of NHL and correlate with certain morphological, immunological and clinical findings. In addition, some aberrations are useful as clonal markers for the detection of (minimal) residual disease. However, due to limited availability of fresh lymphoma tumor tissues, there are only scarce data regarding the prognostic significance of specific genomic aberrations in lymphomas. In all these studies, chromosomal banding analyses were performed retrospectively in heterogeneous groups of patients. In contrast to such banding analyses, molecular cytogenetic techniques, such as comparative genomic hybridization (CGH) do not depend on the availability of fresh tumor samples. Therefore, these methods allow a retrospective genomic screening of archival tissue samples derived from homogeneous groups of patients treated within the same clinical trial.