Posterior epidural migration of free disc fragments is rare, and posterior migration of the free fragments causing cauda equina syndrome is exceptionally rare. This report describes a 53-year-old man with disc fragment extrusion at the levels of L3-4 and a 54-year-old man with disc fragment extrusion at L5-S1 intervertebral space. The patients responded well to the operative therapy with complete relief of the symptoms. The pathological examination confirmed that the specimen was a degenerated intervertebral disc. Early surgery should be the first choice of therapy in patients with large posteriorly migrated sequestered disc fragments, to prevent severe neurological deficits such as cauda equina and conus medullaris syndromes.