Two major surgical procedures, i.e., foramen magnum decompression (FMD) and syringo-subarachnoid shunt (S-S shunt) have been performed as the treatment for syringomyelia with Chiari malformation in our department. FMD was done principally in patients with symptoms due to Chiari malformation and for small size or localized syrinx, and S-S shunt was applied to patients with main symptoms due to syringomyelia, especially with local pain and for large syrinx in size. Eighty patients of syringomyelia with Chiari malformation were surgically treated. FMD was performed in 38 patients, and S-S shunt in 39 patients as the first operation. FMD were done with craniectomy of posterior fossa, C1 laminectomy and resection of epidural band, but without opening dura, and S-S shunt were done with hemipartial laminectomy and DREZtomy. The clinical outcome was evaluated, comparing the two major surgical procedures. Satisfactory neurological improvement was obtained in the two groups, but S-S shunt group took better improvement than FMD group. These results suggest that both procedures are effective, but should be selected by preoperative clinical and radiological findings.