Implantation in the interstitial part of the oviduct is frequently associated with severe fetal and maternal morbidity. We present a patient with primary interstitial and secondary retroperitoneal ectopic pregnancy. The suspicion of an ectopic pregnancy was raised after an ultrasound examination during the 18th week of pregnancy. An almost complete lack of symptoms led us to discard the possibility of an ectopic pregnancy. This normal-course pregnancy advanced to term. Due to anhydramnios and fetal malpresentation, a laparotomy was performed at 39 weeks of pregnancy and a healthy infant was delivered via cesarean section.