In this work the Authors describe the case of a 16-month-old child, who presented neuraxitis infection of cerebellum, during exanthem subitum. From the present etiological considerations about exanthem subitum, referable to human herpes virus type 6, the Authors stress the usefulness of executing the dosage of anti-HHV6 antibodies in all the cases of exanthem subitum and in all febrile convulsions, because it is possible to have atypical clinic forms of VI disease, without exanthem.