In the adult, the primary infection by the varicella-zoster virus acquires an unusual severity due to several complications, the most frequent of them being pneumonia. The authors analyze the clinical, epidemiological, serological and radiological data of the only two cases of varicellous pneumonia in the adult at a general hospital during the past 5 years. They highlight as the main characteristics: easiness of diagnosis, dissociation between clinical and radiological signs and the excellent therapeutical response to the early administration of intravenous Aciclovir. They comment as well the risk factors of this complication and the criteria for hospitalization.