Heterotopic pregnancy is defined as the simultaneous presence of intrauterine and ectopic pregnancies. It is a rare condition, but due to the increasing use of artificial reproductive techniques, the incidence of heterotopic pregnancy is increasing. Most of the patients with heterotopic pregnancy have a previous history of infertility or tubal diseases. In this case series, we are presenting six cases of heterotopic pregnancy. Three of them had a history of assisted reproductive technique: one patient had in vitro fertilization with three embryos transferred, and two patients received follicular stimulating hormone therapy. In one of the cases, heterotopic pregnancy was missed on an initial transabdominal scan, and in the following weeks, it was diagnosed on transvaginal ultrasound. Five patients underwent laparoscopic salpingectomy, and one patient had laparotomy and then a salpingectomy was done. Follow-up ultrasound scans for intrauterine pregnancy (IUP) showed abortion of the IUP, except in one patient who delivered a healthy full-term baby via spontaneous vaginal delivery. Therefore, there is a need to develop diagnostic criteria to rule out heterotopic pregnancy if the patient underwent any type of assisted reproductive techniques. We are emphasizing the need for more careful scanning of the adnexa via transvaginal ultrasound, especially in high-risk patients, even if the intrauterine gestation is confirmed.