The authors described two cases of the ruptured unrecognized interstitial pregnancy. 32-year-old woman, was admitted for abdominal colics in 17th week of uncontrolled pregnancy. Obstetric finding on admission was normal, while ultrasonography pointed to 17th week of gestation. During the first night of hospitalization, severe abdominal pain, with collapse, tachycardia and hypotension developed. Laparotomy was performed in general endotracheal anesthesia with resuscitation measures, and revealed hematoperitoneum and ruptured right-sided interstitial pregnancy with a dead fetus among the bowels. Abdominal hysterectomy without adnexa was performed. S. J., a 35-year-old tertigravida, six years before, left-sided adnexectomy was performed for perforated tubal pregnancy. 5 weeks before artificial abortion now, ultrasonography revealed a vital fetus biometrically corresponding to the 11th week of gestation. The condition was recognized as an unsuccessful artificial abortion and intact pregnancy. During preoperative preparation the patient lost consciousness and required immediate resuscitation. The abdominal cavity was opened by Pfannenstiel's relaparotomy, and revealed hematoperitoneum with numerous adhesions between the small intestine, sigma, uterus and urinary bladder, and ruptured left-sided interstitial pregnancy. Adhesiolysis was completed, a lesion in the sigma was sutured, and hysterectomy was performed. Exploration of the abdominal cavity revealed a dead fetus among small intestine loops, and an indurated, sharply delineated neoplasia of the head of the pancreas.