We assessed by immunohistochemistry the expression levels of the components of the DDR pathway (CHK1, CHK2, CDC25c) and their phosphorylated forms in three reactive lymphnodes, 27 cases of small lymphocyte lymphoma (SLL), 18 marginal zone lymphoma (MZL), 44 Hodgkin lymphoma (HL), 22 Burkitt lymphoma (BL), and 99 consecutive DLBCL cases diagnosed at our Institution from 2002 to 2011. The gene discussed is CHEK1; the disease is diffuse large B-cell lymphoma.