Ganglion cysts usually arise from the tendon sheaths and tissues around the joints. It is usually associated with degenerative arthritic changes in older people. Ganglion cyst in the spine is rare and there is no previous report on case that located in the intervertebral foramen and compressed dorsal root ganglion associated severe radiculopathy. A 29-year-old woman presented with severe left thigh pain and dysesthesia for a month. Magnetic resonance imaging revealed a dumbbell like mass in the intervertebral foramen between second and third lumbar vertebrae on the left side. The lesion was removed after exposure of the L2-L3 intervertebral foramen. The histological examination showed fragmented cystic wall-like structure composed of fibromyxoid tissue but there was no lining epithelium. A ganglion cyst may compromise lumbar dorsal root ganglion when it located in the intervertebral foramen. Although it is very rare location, ganglion cyst should be included in the differential diagnosis for intervertebral foraminal mass lesions.