Primary amebic meningoencephalitis (PAM) is a rapidly progressive and potentially fatal infection frequently contracted by swimming in bodies of warm fresh water. The etiological agent in most reported cases of PAM is the ameboflagellate Naegleria fowleri. Infection with this organism closely mimics and is often mistaken for a bacterial or a viral pyogenic meningitis. Recovery is rare and depends on rapid diagnosis and treatment. Physicians treating individuals who present with an acute pyogenic meningitis should consider the diagnosis of PAM, particularly if the patient has a recent history of swimming in warm fresh water. We review the recent literature for cases of PAM and the discuss ecology of N. fowleri and the clinical presentation, diagnosis, and treatment of PAM.