Internal herniation is a rare cause of acute abdomen. If it is not diagnosed and treated in time, it can cause death. This case report discusses the clinical findings and surgical treatment of a case of left paraduodenal hernia, a rare cause of internal herniation. The diagnosis and treatment process of a 24-year-old female patient with ileus findings was retrospectively evaluated and presented in the literature. The patient was operated on with a preliminary diagnosis of internal herniation and the definitive diagnosis was made intraoperatively. At laparotomy, it was observed that almost all of the small intestines herniated posteriorly from the left paraduodenal region. Small intestinal loops were reduced and the hernia sac defect was primarily repaired. The patient was discharged on the fifth postoperative day with complete recovery. Left paraduodenal hernia is a type of internal herniation that should be considered in the differential diagnosis of patients with recurrent abdominal pain and intestinal obstruction. Surgical reduction and primary repair of the defect is an appropriate treatment.