We have synthesized a 17-mer peptide (ER17p) that is issued from the hinge region of the estrogen receptor and which activates the proliferation of breast carcinoma cells in steroid-deprived conditions. In the present paper, we show that at a concentration of similar to 50M, it rapidly forms amyloid-like fibrils with the assistance of electrostatic interactions and that at higher concentrations, it spontaneously forms a hydrogel. By using biophysical, spectral and rheological techniques, we have explored the structural, biophysical and mechanical characteristics of ER17p with respect to fibril formation and gelation. Copyright (c) 2014 European Peptide Society and John Wiley & Sons, Ltd.