Abstract: Objective To explore the diagnosis and treatment of sacral arachnoid cysts. Methods A retrospective analysis of the clinical manifestations, MRI features, and surgical outcome was conducted in 20 patients with sacral arachnoid cysts. Results Of the 20 patients, 12 and 8 underwent total and subtotal resection of the cysts, respectively. Neurological functions were improved with no relapse of cysts during the 2-24 months follow-up period. Conclusion Sacral arachnoid cyst typically occurs at a dorsal extradural location, usually complicated by congenital sacral canal deformity and prolapse of lumber intervertebral disc. MRI is an effective method for the detection of sacral arachnoid cysts. Microscopic total or subtotal resection of cysts can sufficiently decrease the pressure and protect the nerves and treat the complications of congenital sacral canal deformity and prolapse of lumber intervertebral disc. Ligation of the" traffic hole"and filling of the cyst cavity can effectively prevent relapse of such cysts.