A case of primary amebic meningoencephalitis (PAM) with severe spinal cord involvement was documented in a 12 year-old boy from Samut Prakan Province, Thailand. This is the first reported case of Naegleria meningomyeloencephalitis in Thailand. He had a history of swimming in the canal nearby his house prior to the fever, headache and convulsion which rapidly progressed into a comatose state. PAM was only detected at post-mortem. The findings included suppurative exudates and necrosis of the olfactory bulbs and the basal parts of the frontal, temporal lobes, pons, cerebellum, medulla and the spinal cord. Numerous Naegleria trophozoites were present in the brain and spinal cord. Foci of neuronal degeneration and demyelination were noted.