Heterotopic pregnancies are estimated to be less frequent than 1:30000 if no assisted reproduction technologies (ART) are performed. After ART this entity is more frequent and in the range of 1:100. In the case reported here an ectopic pregnancy was detected in the right fallopian tube at 7+ 1 weeks of gestation. It was misdiagnosed as an ectopic singleton, and treated by laparoscopic salpingectomy, because of a previous ectopic in the same tube. Rising hCG after laparoscopy during the subsequent days followed by ultrasound evaluation revealed a viable intrauterine pregnancy. The pregnancy continued uneventfully and a healthy child was delivered at term. The problems, which lead to the misdiagnosis are discussed. The problem of rare cases in medicine, and the problems of a 'modern' medicine are discussed.