Background: Conjoined twins have invariably been a subject of revulsion among many societies across the world despite the fact that they can be diagnosed early in pregnancy and optimal obstetric management instituted accordingly. Case Presentation: We present a case of a prenatally undiagnosed derodidymus (dicephalous diauchenos) twins, an extremely unusual variant of conjoined twins. The case was such a petrifying unanticipated phenomenon to both the parents and medical staff. Conclusion: Routine prenatal ultrasonograhy and careful prenatal screening must be strongly emphasized if we are to minimize such perinatal mysteries.

Keywords: Case report, conjoined twins, derodidymus, dicephalous diauchenos, Siamese twins