Sacral hernias are uncommon defects developing through the pelvic floor after partial or total sacrectomy. We report on a 29-year-old woman, who has been under our care with a cystic formation after perineosacral resection of a rhabdomyosarcoma and partial sacrectomy. The cystic tumor was resected and a mesh repair performed to prevent sacral herniation. The current literature is summarized; etiology and management recommendations of this rare complication are discussed.