In the last years the entire scientific community has devoted remarkable resources to the understanding of endometriosis. In spite of this, endometriosis remains one of the most complex gynecological diseases, in nearly all of its physiopathological aspects and implications. In particular, the association between endometriosis and infertility has proven to be complex and it has been widely discussed. It is generally accepted that moderate/severe endometriosis related sterility is due to mechanical factors, namely to the distortion/subversion of the regular pelvic anatomy. On the contrary, the factors behind infertility/subfertility related to minimal/mild endometriosis are less clear. None of the hypothesized mechanisms exhaustively explained the infertility related to endometriosis, while it is possible that such disease is caused by multiple factors altogether. The aim of this thorough review of the international literature is to analyze the main etiological factors (i.e. alterations in oocyte maturation and/or growth, defects of fertilization, impairments of implantation or aberrant immunological mechanisms) that are potentially involved, as well as the role that each of the above mentioned factors has in determining the endometriosis related infertility/subinfertility.