The purpose of this study is to put forward a new theory about the genesis of the prologue of Euripides' Iphigenia at Aulis through a critical analysis which includes a detailed textual criticism of the vv. 1-163 (the iambic and anapaestic prologue) and an inquiry which involves not only euripidean tragedy and/ or his interpolators but even the so-called 'Middle Comedy': the structure of this kind of comedy, actually, could be very similar to the prologue of euripidean Iphigenia. So we have a new possibility of discussing this text - partly compromised by corruption of the manuscript tradition - through the relationships between literary genres.