the case of a patient with a clinically suspected west nile virus encephalitis is described. the patient is a 70 year male with a 7 day fever who developed confusión, speaking difficulties and generalized muscular weakness. since the patient' s condition improved, he was discharged from this hospital seven days after admission. twenty days later, west nile virus igg antibodies were found high through elisa method. the case was retrospectively reviewed and it was classified as possible west nile virus encephalitis. the results if igg antibodies for west nile virus obtained by the elisa method, as well as the clinical features of the patient are consistent with west nile virus infection according to the cdc criteria.