The authors reviewed the clinical findings and treatment results of 12 cases of spinal meningeal cysts which were detected in MRI of low back patients. In these lesions, large cysts without CSF communication can compressed the nerve roots within spinal canal and it is difficult to confirm the cause of symptom whether it is originated from cysts or from associated spinal disorders. The terms and classifications of spinal meningeal cysts were very confusing. Among 12 cases, we excised 3 cases of large cysts with gluteal and perianal pains that were caused by compressed sacral nerve roots. All three cases were type 2 cyst (classified by Nabors) and located in sacral canal. In one case associated with isthmic spondylolisthesis, posterolateral fusion and pedicle screw fixations were combined with cyst excision. In other two cases, there were not any spinal pathologic findings that compressed sacral nerve roots except mild degenerative changes and intervertebral disc herniation in lower lumbar and sacral levels All 3 excised cases showed good prognosis in more than one year follow up. The other cases were treated conservatively for the associated spinal disorders.