Persistent cloaca is a rare abnormality that occurs usually in females and is characterized by direct communication between the gastrointestinal, urinary,and genital structures resulting in a single perineal opening. We report a case of persistent cloaca accompanying uterus didelphys that was diagnosedantenatally with fetal ultrasonography. A gravida 3, para 2, 35-year-old women at 22 weeks of gestation was referred to our hospital with a diagnosis ofmoderate pyelectasis of the fetal kidneys and fetal diffuse intestinal dilation. Detailed ultrasound scan findings were reported as a small thick-walled septatedcystic pelvic mass of 5.2×5.5 cm size seen at the level of the fetal pelvic region. The target sign could not be visualized, it was considered as anal atresia.In the following weeks, the patient, who was evaluated together with meconium on the uterine septum, and monitoring of the neighboring bladder andanal atresia, was diagnosed as having persistent cloaca. Ultrasound findings showed that it could be persistent cloaca accompanying uterus didelphys. Thefetus postnatally manifested persistent cloaca. On the first day after vaginal delivery, pelvic ultrasound in the neonatal intensive care unit showed bilateral2nd-degree hydronephrosis, presacral enlarged bowel loops, uterus didelphis, vaginal septum, direct contact between urethra and vagina, proximal endin the rectum compatible with atresia. On the second day, colostomy was performed. Her renal condition continued to be stable. She is now waiting fordefinitive surgery for cloaca. Persistent cloaca should be considered in any female fetus presenting with hydronephrosis and a cystic pelvic mass lesion asdiagnosed by ultrasound. Prenatal diagnosis allows time for parental counseling and delivery planning at a tertiary hospital for neonatal intensive care andpediatric surgery.