Pregnancy implanted in the rudimentary horn of unicornuate uterus is very rare with an incidence of 1 in 75,000 to 1 in 150,000 pregnancies. Both prerupture and postrupture diagnosis of ectopic pregnancy in the rudimentary horn of a unicornuate uterus is difficult. Here is a case of a 21-year-old gravida 5 para 3 abortion 1 mother presented with abdominal pain of 2 days duration following a falling accident. The patient was severely anemic and was in hypovolemic shock at the time of presentation. She had diffused lower abdominal tenderness with hemoperitonium. After clinical and ultrasound evaluation, emergency laparotomy was decided for preop diagnosis of ruptured cornual ectopic pregnancy to rule out uterine rupture at gestational age of 16 weeks. Intraoperatively, ruptured ectopic pregnancy in noncommunicating rudimentary horn was diagnosed. Resection of rudimentary horn and ipsilateral salpingectomy was done. She was transfused with 5 units of compatible blood. It is better to increase awareness about pregnancy occurring in this rare uterine anomaly, so as to have a high index of suspicion as early detection before it gets ruptured is difficult.