CD4+ helper T (Th) cells are critical regulators of immune responses but their role in breast cancer is currently unknown. This work aims to characterize Th cells infiltrating invasive primary human breast tumors, analyze the influence by the tumor microenvironment and identify Th cell specific prognostic gene signatures. CD4+ T cells isolated from the tumor (TIL), axillary lymph node (LN) and blood (PB) of 10 patients were analyzed on Affymetrix U133 Plus 2.0 arrays. A confirmation set of 60 patients were studied by flow cytometry, qRT-PCR or immunohistochemistry and analyzed according to the extent of the tumor immune infiltrate. Gene expression profiles of freshly isolated TIL were also compared with TIL that had been rested overnight or with CD4+ T cells [non-stimulated (NS) or stimulated (S)] from healthy donor PB treated with tumor supernatant (SN).