Retro-rectal cystic hamartoma (tailgut cyst), is an uncommon congenital developmental lesion, generally located in the retro-rectal space. Its diagnosis and approach is challenging because the retropelvic space is not familiar. We report a 51-year-old woman who presented with paresthesia and pain in perianal area. The magnetic resonance image showed high signal intensity on the T1-weighted image and iso to high signal intensity on the T2-weighted image of the retropelvic space and CT showed sacral bony defect. We chose the posterior approach for removal of the tailgut cyst. Histopathology exam of the retropelvic cyst revealed a multiloculated cyst containing abundant mucoid material lined by both squamous and glandular mucinous epithelium. The patient has recovered nicely with no recurrence. Tailgut cyst needs complete surgical excision for good prognosis. So, a preoperative high-resolution image and co-operation between neurosurgen and general surgeon would help to make safe and feasible diagnosis and surgical access.