Rocky Mountain spotted fever (RMSF), an acute febrile exanthematous illness caused by Rickettsia rickettsii and transmitted by ticks, is endemic in the southern Atlantic states [USA]. A report is given of the clinical and pathological findings of myocardial involvement in 16 children who died with severe RMSF. All 16 children had myocardial lesions to some degree, but it was not believed that these could be evaluated in terms of cardiac function and death in the face of the usual peripheral vascular collapse caused by the widespread vascular lesions throughout the body.