Heterotopic pregnancy is defined as the rare presence of simultaneous pregnancies at two different sites of implantation, one intrauterine and the other extrauterine (ectopic). It is a life-threatening condition that can be easily missed if not noticed carefully. Here, we present a case report of heterotopic pregnancy diagnosed by ultrasonography in a patient. Once an intrauterine gestational sac is visualized, the radiologists are relieved and do not inspect the adnexa carefully even if ectopic pregnancy is clinically suspected. One should remember “Think ectopic. If intrauterine gestation is seen, think heterotopic.”