A 55-year-old white man with severe scoliosis and chest deformity was scheduled for an intercostal neurolysis for pain relief with 7.5% aqueous phenol solution. A 20 G needle was inserted 3 to 4cm lateral to the midline of the spine under the 10th right rib. After negative aspiration for blood and alcohol, 6mL of a 7.5% aqueous phenol solution was injected. Within a minute after the injection, the patient felt a warm sensation in his right leg, followed by loss of leg motor and sensory function on both sides. A lumbar puncture done 3.5 hours after the block showed a phenol concentration of 87.5 microg/mL. The most likely explanation is a diffusion of the phenol through the intervertebral foraminae reaching the spinal space and therefore damaging the motor and sensory roots. This case highlights the danger associated with phenol application in the vicinity of the spinal cord.