OBJECTIVE: Breast cancer (BC) is a heterogeneous disease, recognized as a major public health problem worldwide, with several risk factors including oxidative stress, an imbalance between the production of reactive oxygen species (ROS) and antioxidant capacity. The aim of this study is to evaluate oxidative stress markers 8-Hydroxydeoxyguanosine (8-OHdG) and protein carbonyl and their associations with pathological and immunohistochemical parameters as well as the immune system in particular Interleukin-6 (IL-6) in BC patients from western Algeria. METHODS: We analyzed serum concentrations of 8-OHdG and IL-6 by Eliza technique and protein carbonyl by derivatization of protein carbonyl groups with 2,4-dinitrophenylhydrazine (DNPH), then associated them with immunohistochemical and pathological parameters, as well as in the different molecular and histological groups of BC. RESULTS: Our results show that there was no significant difference in serum concentrations of 8-OHdG and protein carbonyl, between controls and patients, and a negative correlation between these markers and lymph node count as well as with proliferation protein Ki-67. We also found a significant association between the DNA oxidation marker 8-OHdG and Human epidermal growth factor receptor 2 (HER2) expression. No association was found between oxidative stress markers and IL-6. Furthermore, no significant differences in serum levels of 8-OHdG and protein carbonyl were found in the different histological types and molecular classes of BC. CONCLUSION: Our results show that our patients do not have oxidative stress and that physiological ROS concentrations represent a good prognostic indicator, particularly in cancer cell proliferation through their negative correlation with Ki-67, and also metastatic lymph node count. Moreover, HER2 probably has the capacity to modify the state of oxidative stress, notably DNA oxidation. Finally, different molecular and histological types of BC have the same oxidative stress level and antioxidant capacity.