The authors discuss the problem of rickettsial and para-rickettsial etiopathogeny of some types of angiopathies earlier characterized by a febrile state. They are especially interested in vasculopathies occurring in endemia areas. The disease may involve the entire vascular system and the pathogenic agent remains in the mid membranes and in the adventitia, as can be seen by seriologic and anatomo-pathologic tests. There are diffuse or nodular lymphoblastic infiltrations (pan-vascular condition). The authors also demonstrate that treatment with higher tetracyclines (Reverin) is absolutely advised, and draw attention to the need to do systematic seriologic research on all patients hospitalized for cardio-vascular diseases.