Endometriosis is a very challenging condition. It is a gynecological enigma. The true incidence of pelvic endometriosis in women still remains largely unknown, despite several studies quoting variable figures. Chronic pelvic pain and infertility have been the most common features in women with endometriosis. However, the cause/effect relationship between endometriosis and infertility remains a subject of debate. Endometriosis is found to be more in nulliparous women & women with pelvic pain and less among fertile women and women with amenorrhoea. We now believe that retrograde menstruation is probably the cause for the occurrence of pelvic endometriosis. We proposed that infertility or non-conception with persistent menstruation for several years after menarche most likely lead to endometriosis, which when it leads to adhesions further compromises fertility. We strongly believe that it is not the other way that (Endometriosis causes Infertility) around as is commonly believed.