A case of isolated infective endocarditis of the pulmonary valve in a patient with known subpulmonary interventricular septal defect that had, as major complication pulmonary septic embolization, was reported by the authors. The disease followed an insidious course, diagnosed by the presence of vegetations in the echocardiogram, some of them larger than 1 cm. They were found in the right ventricular infundibulum and in the pulmonary valve leaflets. The isolation of Estreptococcus viridans in blood cultures has confirmed the diagnosis. In spite of appropriate antimicrobial therapy, according to the antibiogram data (with Ampicillin and Gentamicin), fever lasted for more than three weeks. This event suggested medical treatment failure and the possibility of surgery was considered. However, the endocarditis eventually healed with medical therapy alone, and this unusual course with prolonged fever was presumed to be caused by lung metastatic infection secondary to septic embolization. This complication is relatively common, but lung involvement is usually a subclinical event, not responsible for such persistent fever, as happened in the case now reported. We emphasize the rarity of this case, the unusual clinical course and the discussion concerning the therapeutic options.