Prune belly syndrome (PBS) is characterized by a classical triad of congenitally absent abdominal muscles, bilateral cryptorchidism, and a malformed urinary tract. Urorectal septum malformation sequence (URSM) is identified with the absence of urogenital and anal openings. This case report describes a 15-week-old female fetus with megacystis, ascites and oligohydramnios in a 19-year-old nulliparous woman. The patient underwent preterm labor at the 33rd gestational week and delivered a female newborn weighing 2250 grams who died three days later due to progressive respiratory insufficiency. To the best of our knowledge, this is the third case of an overlap between PBS and URSM in literature. Such an overlap refers to the existence of left renal agenesis, right renal cystic dysplasia, bilateral club foot and lumbar scoliosis as well as the absence of abdominal wall muscles, internal genital organs, urethral, vaginal and anal openings. This case report aims to remind the obstetricians about the concurrent occurrence of PBS with URSM and its poor prognosis.