It is generally thought that if patients with ehrlichiosis are treated promptly, life-threatening illness can be avoided. We report a patient who sought medical attention 1 day after the onset of symptoms, was immediately given doxycycline, and still had serious illness with generalized edema, pulmonary infiltrates, acute respiratory distress syndrome, and noncardiogenic pulmonary edema, while receiving replacement intravenous fluids. This case alerts physicians to the serious end of the disease spectrum that can occur even though patients are given prompt, appropriate drug treatment at the onset of illness. Further studies are needed to clearly define the mechanisms involved in pulmonary complications and generalized edema, including noncardiogenic pulmonary edema, in patients with ehrlichiosis.