Nitrous oxide (N₂O), an anesthetic gas, has been abused by some people for entertainment purposes. Recently, N₂O (under the name of "Happy Balloon") abuse has become problematic among young people in Korea. N₂O intoxication can develop a neuropathy, as well as other systemic disorders, either by inactivating vitamin B12 or by a direct neurotoxic mechanism. Here, we report a case of peripheral neuropathy with possible coexisting myelopathy following N₂O abuse.