The Triple Negative " Basal-like " breast cancer (TNBL) tumours have a high proliferative capacity and develop a resistance phenotype associated with me-tastases. However, the management of TNBL carcinomas is still not standardized. Among the promising trails, gold nanoparticles could be a relevant tool for the development of a targeted treatment for this breast cancer sub-type in monotherapy, associated and/or conjugated with other drugs. In this work, we report the cytotoxicity impact of gold nanoparticles wrapped in Poly-Ethylene Glycol (PEG) on the TNBL HCC-1937 breast cancer cell line. PEG-coated gold nanoparticles (PEG-Au NPs) were synthesized by a two-step method using a reduction process followed by a post-functionalization called PEGylation. PEG-Au NPs were characterized using transmission electron mi-croscopy and X-ray diffraction. The gold content of the samples was determined using atomic absorption spectrometer. The cytotoxicity tests were performed using Sulforhodamine B survival test and resazurin viability test. PEG-Au NPs impact analysis on HCC1937 TNBL cell line showed a clear toxic action of type dose dependent and at long term. These PEGylated gold nanopar-ticles present a promising tool for the development of tumor-specific radi-osensitizing vectors, with or without the association of other treatment strategies .