Dnmt3b is a tumor suppressor in oncogene-driven lymphoid and myeloid malignancies in mice. However, it is poorly understood whether reduced Dnmt3b activities can initiate malignant hematopoiesis. We modulated Dnmt3b activity in vivo by generating Dnmt3b+/− mice expressing one wild-type allele. Here, we analyzed methylation and gene expression in Dnmt3b+/- peripheral T-cell lymphomas (PTCLs). Overall design: We performed WGBS and RNA-seq analysis on Dnmt3b+/- peripheral T-cell lymphoma samples isolated from lymph nodes of terminally sick mice. WGBS experiments were performed in biological duplicates, RNA-seq experiments in triplicates. In addition we performed WGBS of Dnmt3a -/- PTCL.