AIMS: Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with various genetic alterations. The aim was to investigate MYC, Bcl-2 and Bcl-6 translocations and copy number changes in adult DLBCLs to evaluate their clinicopathological features and prognostic implications. METHODS AND RESULTS: Gene status was examined using fluorescence in situ hybridization (FISH), and the results were analysed in the context of germinal centre B-cell (GCB) and non-GCB type of DLBCL based on immunohistochemistry. MYC translocation was observed in 9% (14 of 156), and an increased copy number (ICN) in 7.1% (11 of 156). MYC translocation was more common in GCB type (22%) than in non-GCB type (4.9%), and associated with advanced International Prognostic Index (IPI). MYC aberration, i.e. translocation or increased copy number (ICN), was significantly associated with shorter overall survival, especially for the GCB type. Bcl-2 translocation was rare (3.4%, five of 145), and ICN was observed in 11.7% (17 of 145), more frequently in non-GCB type (16%) than in GCB type (2.5%). Bcl-2 aberration tended to have an adverse effect on survival. In multivariate analysis, MYC ICN was an independent poor prognostic factor. CONCLUSIONS: Analyses of MYC and Bcl-2 status, i.e. translocation and ICN, in the context of DLBCL phenotype might help predict prognosis and determine therapeutic strategies.