The objective of this study was to determine the frequency of expression of GRP78 and BIK/NBK proteins, as well as to evaluate their correlation with prognostic factors for clinical use in patients with locally advanced breast cancer (LABC) or preoperative chemotherapy (PC). An observational, analytical and retrospective study that evaluated the expression of BIK/NBK and GRP78 by means of immunohistochemistry in paraffin-embedded tumour tissue samples obtained before the start of PC was executed. GRP78 was positive in 93.3% and BIK/NBK was positive in 40% of the samples analysed. Correlation of GRP78 expression with Ki67 expression (Rho = 0.732, p = .039), and of BIK/NBK expression with Ki67 expression (Rho = 0.777, p = .023) and number of residual lymph nodes (Rho = 0.619, p = .014) was observed. Given the correlation observed, association studies of the expression of GRP78 and BIK/NBK with clinical and pathological response, recurrence and survival should be carried out in a greater number of patients with LABC or PC.