SummaryA 53 male patient presents signs of myocarditis with congestive heart failure, together with typical crisis of rheumatic fever. Afterwards, he develops a lymphocytic polyserositis in which no Koch Bacillus can be demonstrated.A diagnosis is established of active rheumatic polyserositis and myocarditis. A treatment with cortisone is performed.The patient dies a few days later. Autopsy discloses a miliary tuberculosis.In connection with this observation, the author relates some analogous cases found in the literature. He stresses the dangers of cortisone therapy which may foster the spread of various infections and particularly of tuberculosis.