Pure word deafness is a rare disorder dramatically impairing comprehension of spoken language, while auditory functions remain relatively intact. We present a 71-year-old woman with a slowly progressive disturbance of speech perception due to pure word deafness. MRI revealed degeneration of the temporal lobes. A magnetoencephalographic investigation using alternating single tone stimulation showed that N100 was followed by a second transient response and was abnormally prolonged up to 600-700 ms. We conclude that auditory processing is disturbed at long latency ranges following the N100, which may result in the clinical presentation of pure word deafness.