Unicornuate uterus with rudimentary horn occurs due to failure of complete development of one of the Mullerian ducts and incomplete fusion with the contralateral side. It is associated with numerous obstetrics and gynecological problems such as Infertility, Endometriosis, Miscarriages, Malpresentations & Intrauterine growth restriction. Pregnancy in the non-communicating rudimentary horn is extremely rare and usually terminates in rupture during first or second trimester of pregnancy. Pregnancy occurs via transperitoneal migration of sperm or zygote. Variable thickness of rudimentary horn musculature, poor distensibility of myometrium lead to rupture. This complication is usually seen in 2nd trimester resulting in shock and haemoperitoneum. Diagnosis of rudimentary horn pregnancy is difficult and can be missed in ultrasound. It requires a high risk of suspicion. Materials and Methods: We report the case of 24yr primi gravida with 26 weeks of gestation presented with pain abdomen and sudden maternal collapse on arrival, suspected to be intra-abdominal pregnancy in ultrasound and on laparotomy found ruptured rudimentary horn of unicornuate uterus with fetus found intra-abdominally with massive hemoperitoneum. Conclusion: Pregnancies in rudimentary horn of unicornuate uterus are prone to intra uterine growth restriction and rupture in second trimester so a high index of suspicion is required to save this catastrophic event and associated maternal morbidity and mortality. In our opinion, routine excision of rudimentary horn should be undertaken during non-pregnant state laparoscopically. However, those women who refuse should be adequately counseled regarding potential complications and if pregnancy occurs in rudimentary horn, first trimester laparoscopic excision should be done.