Women diagnosed with triple negative breast cancer can benefit neither from endocrine therapy nor from HER2-targeted therapies (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We report here significant differential expression of the gene encoding mitochondrial ribosomal protein L13, MRPL13, when comparing the tumor cells of patients with triple negative breast cancer to normal mammary ductal cells (2). MRPL13 was also differentially expressed in bulk tumor in human breast cancer (3). MRPL13 mRNA was present at significantly increased quantities in TNBC tumor cells relative to normal mammary ductal cells. Analysis of human survival data revealed that expression of MRPL13 in primary tumors of the breast was correlated with recurrence-free survival in patients with basal-like, luminal A, luminal B and HER2+ type cancer, while within triple negative breast cancer, primary tumor expression of MRPL13 was correlated with recurrence-free survival in patients with basal-like 1 subtype disease. MRPL13 may be of relevance to initiation, maintenance or progression of triple negative breast cancers.