Q fever is a zoonosis found worldwide and is produced by Coxiella burnetii. It may be acute or chronic with neurological manifestations being infrequent. Several cases of acute encephalitis or meningoencephalitis have been described, generally with an evolution towards cure regardless of the use of selective antibiotic treatment. Recently the authors had the opportunity to study a 33 year old male presenting acute meningoencephalitis in which the clinical manifestations, CSF findings (increase in cellularity with lymphocytic predominance and excess proteins ) and neurophysiological findings (appearance of periodic bilateral complexes in the EEG) suggested the diagnosis of herpetic meningoencephalitis. Treatment with acyclovir was initiated. However, serologic studies demonstrated, a posteriori, that the germ responsible had been Coxiella burnetii. The patient evolved satisfactorily with no specific treatment and the EEG anomalies disappeared within a few days. The authors insist on the need to include Q Fever in the diagnostic differential of acute meningoencephalitis and emphasize the possibility that germs of a non viral nature may produce periodic EEG complexes in all that similar to those found in herpetic encephalitis.