ERBB2, a ligand-less membrane receptor, is frequently overexpressed in a number of human tumors, contributing to uncontrolled cell proliferation. In some cases, gene amplification correlates with protein overexpression and predicts response to trastuzumab. We analyzed the expression of ERBB2 in a group of 40 patients diagnosed with infiltrating squamous cervical carcinomas (ISCC) using a microarray. Immunochemistry was performed using two different antibodies, one against the extramembrane domain and the other one for the intramembrane domain. Ten of the 40 cases included in the study could not be evaluated. Of the 30 remaining biopsies, 13 (42%) showed immunoreactivity only with the antibody against the intramembrane domain. In 5 (16.12%), both intramembrane and extramembrane immunoreactivity was observed, and 12 (40%) were negative for both antibodies. Looking at our results, we propose that, in some ISCC, there is a rupture of the ERBB2 receptor, and this event, with slight genetic amplification, could explain the unfavorable response to trastuzumab observed in some ISCC descript for some authors.