A 27-year-old woman, gravida 1, was seen at our surgical emergency department with abdominal pain at 25 weeks' gestation. She had pain, nausea and vomiting, a temperature of 37°C and a blood pressure of 100/70 mmHg. The cervix was closed, and an ultrasound scan showed a normal single fetus. A plain abdominal radiograph showed distension of the colon and a sigmoid volvulus. At emergency laparotomy, non-gangrenous sigmoid colon was resected with primary anastomosis. There were no complications, and 4 months later the patient delivered a healthy infant. Early diagnosis of sigmoid volvulus in pregnancy and prompt intervention minimise maternal and fetal morbidity and mortality.