A case of primary amoebic meningoencephalitis caused by Naegleria, from Sisaket province of Thailand is first reported. A 5-year old Thai with boy a history of swimming in a pond along a rice field before the onset of this illness, was admitted to the provincial hospital for chief complaints of headache, high fever, vomiting and drowsiness for 4 days. On admission he had convulsions and became comatosed with signs of meningeal irritation. The cerebrospinal fluid was similar to pyogenic meningitis but numerous amoebae were found and identified as Naegleria sp. Unfortunately, specific treatment was not administered promptly, the patient died 3 days after admission.