The authors report four observations of rickettsioses with R. conori (3 cases) or R. mooseri (1 case) with pericardial, pleural or pulmonary manifestations (2 cases). On this occasion, they recall that diagnosis of rickettsiosis can only be made on precise conditions: compatible clinical syndrome, significantly increasing then decreasing antibodies level, negative bacteriological and viral investigations and effectiveness of particular antibiotics. They also recall the main characteristics of pericardites, pleurisies, and pneumopathies produced by rickettsiae, probably more frequently than previously thought.