Background: Huntingtin Interacting Protein 1 (HIP1) is a binding protein to inositol and clathrina that is related to neurodegeneration. Signaling of growth factors receptors trought clathrina is one of the mechanisms by which cells regulate the intracellular signaling. There have been observed high levels of HIP1 protein in breast, colon, kidney, lung, melanoma, ovarian and prostate cancer. Furthermore, HIP expression was negatively correlated with survival in prostate cancer. HIP1 overexpression has been shown to inhibit the degradation of EGFR and estrogen receptor. EGFR expression has been correlated with response to chemotherapy in triple negative breast cancer. Methods: Tumor biopsies were obtained from 83 breast cancer patients (p) treated with neoadjuvant chemotherapy, based on four cycles of fluorouracil, epirubicin and cyclophosphamide. Estrogen receptor, progesterone receptor, HER2, cytokeratin 5/6, vimentin and HIP1 were examined by tissue microarray. HER2 were also assessed by chromogenic in situ hybridization. We evaluated the prognostic and predictive value of HIP1 expression. Results: HIP1 was evaluated by immunohistochemistry in 83 p, being considered negative if the result was 0 or 1, and positive if it was 2 or 3. The result was 0 in 11 p (13.3%), 1 in 40 p (48.2%), 2 in 25 p (30.1%), and 3 in 7 p (8.4%). The value of huntingtin did not correlate with any of the clinical characteristics of the series, nor with ER, PR, vimentin, or HER2, nor subgroups. Negative HIP1 was correlated in the limit of significance to positive CK5 /6. Overexpression of HIP1 was correlated to higher pathologic response, as shown in table 1. HIP1 was not statistically correlated to DFS or OS, but p with overexpression of HIP1 had a median survival of 50 months whereas it was 67 months for p without overexpression of HIP1. Conclusions: HIP1 could be a prognostic and predictive factor in breast cancer. Showing that HIP1 is necessary for breast cancer progression and modulates key growth factor receptors involved in breast cancer, fuels the idea that HIP1 inhibition has therapeutic potential.