Fatal Mycoplasma pneumoniae infection in a 30-yr-old woman is described. After 9 days of symptoms, the patient developed severe respiratory distress, rapidly progressive pneumonia, cardiovascular collapse, and acute renal failure. Death occurred 24 h after hospital admission. Postmortem examination demonstrated a diffuse membranous laryngotracheobronchitis, massive bilateral pneumonia, disseminated intravascular coagulation with widespread renal involvement, and hemorrhagic necrosis of the adrenal glands. Mycoplasma pneumoniae was isolated from the trachea, lungs, kidney, and brain, indicating hematogenous dissemination of the organism from its portal of entry in the respiratory tract.