Introduction Heterotopic pregnancy refers to the presence of simultaneous pregnancies in two different implantation sites, intrauterine and ectopic pregnancy, 90% in the fallopian tubes. It is a rare but life-threatening condition. The risk of heterotopic pregnancy is increasing due to assisted reproductive techniques, with an incidence of 1/4.000 pregnancies, being extremely rare in spontaneous pregnancies with an incidence of 1/30.000 pregnancies. We report two interesting cases, one after induction of ovulation and one after spontaneous conception. Case presentation We studied the cases of two patients who self-referred to our unit for the first prenatal visit. The patients were both of Caucasian ethnicity, aged 30 and 38 respectively, both having amenorrhea of 6-7 weeks, both with positive home pregnancy test. First patient obtained the pregnancy spontaneously, the other after medical treatment for anovulation. Both patients were admitted with suspicious of heterotopic pregnancy and within the first 24 hours the diagnosis was confirmed. Surgical treatment was offered and our patients were discharged after 3 days. For both patients we obtained the histological confirmation of the diagnosis after surgery. Conclusions This rare and life-threatening condition should be promptly recognized and managed accordingly. Sonographic identification of an intrauterine gestational sac is suggestive, but not diagnostic, of an intrauterine pregnancy. Attention should be paid while assessing the pelvic organs after diagnosing a uterine pregnancy. Fluid in the pouch of Douglas and new onset acute abdominal pain should rise awareness.