CASE PRESENTATION: A 43 year-old woman presented with fever, dyspnea and polyarthralgias for several weeks. Physical exam was notable for temperature 102.7, IV/VI systolic murmur at the apex, and right-sided crackles. There was tender synovitis of the bilateral wrists and knees. Chest radiograph showed diffuse infiltrates, right greater than left. Electrocardiogram showed PR-interval prolongation (0.25ms). She was treated with antibiotics for pneumonia, but developed hypoxic respiratory failure requiring mechanical ventilation. Bronchoscopy revealed progressively bloody return. Echocardiography revealed severe mitral regurgitation with ruptured chordae tendinae of anterior and posterior leaflets. Sedimentation rate was 124 and antistreptolysin-O titer was >2300 IU/ml. Respiratory cultures, respiratory viral panel, and mycoplasma, legionella, and HIV tests were negative. Antinuclear antibodies, antineutrophil cytoplasmic antibodies, and antiglomerular basement membrane antibodies were negative. She was diagnosed with DAH due to rheumatic fever with mitral valve involvement. Penicillin therapy was begun and she was taken for urgent mitral valve replacement. Pathologic evaluation demonstrated severe acute and chronic inflammation of the anterior and posterior leaflets consistent with rheumatic valve disease.