Although oxidative stress plays an important role in the biology of solid malignant tumors, little is known about oxidative stress in hematological malignancies. In this study, we evaluated the immunohistochemical expression and clinical correlations of oxidative stress markers and several essential antioxidant enzymes in B-cell lymphomas. Paraffin-embedded diagnostic tissue samples from 18 diffuse large B-cell lymphomas (DLBCL), 18 follicular lymphomas (FL), 19 Hodgkin lymphomas (HL), 7 chronic lymphocytic leukemias (CLL), 7 mantle cell lymphomas (MCL) and 7 mucosa-associated lymphoid tissue (MALT) lymphomas, together with samples from 6 reactive lymph nodes were stained for oxidative stress markers 8-hydroxydeoxyguanosine (8-OHdG) and nitrotyrosine and antioxidant enzymes manganese superoxide dismutase (MnSOD), thioredoxin (Trx) and γ-glutamyl cysteine synthetase (γ-GCS). There was increased 8-OHdG reactivity in DLBCL compared to more indolent lymphomas and reactive lymph nodes. Positivity for Trx was most intense in HL. In DLBCL, positivity for 8-OHdG and nitrotyrosine associated with shorter survival (p = 0.032 and p = 0.026, respectively). This study showed increasing expression of oxidative stress markers and antioxidant enzymes in a series of lymph node samples evolving from reactive lymph nodes to indolent and aggressive lymphomas. These markers seem to have strong prognostic value, but this has to be verified in larger studies.