Purpose Endometriosis is a benign estrogen-responsive disease which shares some characteristics with malignant tumors such as invasion and unrestrained growth. In this respect, the epidermal growth factor receptor family (EGFR or erbB-1 and erbB-2 to -4) is known to play an important role in tumor biology. The aims of the present study were: 1) to investigate the expression patterns of the four erbB receptors, 2) to ascertain if there was a correlation between the EGFR family expression and the expression of the estrogen receptor α (ERα). Methods Retrospective study: 48 peritoneal and 12 ovarian human endometriotic lesions were analyzed by immunohistochemistry. The confirmation of the immunohistochemical findings was made by Western blot analysis. Using the Mann-Whitney-U test, statistical analysis was performed. Results In peritoneal and ovarian endometriosis, all members of the EGFR family and ERα are detectable in stromal and epithelial cells, but the expression is different within the tissues. Only in ovarian endometriosis was a statistical association observed between EGF receptor and ERα expression (p