To the Editor. —Infections in patients with AIDS often represent challenging diagnostic problems, and all the means of obtaining diagnostic clues must be actively pursued. We recently saw a patient with AIDS and Kaposi's sarcoma who was admitted to the hospital because of high fever of one month's duration, weight loss, and abdominal pain. Prior to the onset of these symptoms, intermittent diarrhea had been present for two months. Before admission, stool examination revealed cysts of Giardia lamblia and Entamoeba histolytica . On admission, his temperature was 39 °C, his BP was 120/70 mm Hg, and his heart rate was 120 beats per minute. His skin showed the violaceous maculopapular and nodular lesions characteristic of Kaposi's sarcoma. The abdomen was distended with diminished bowel sounds and pronounced tenderness in the right upper quadrant. Hepatosplenomegaly was present. Laboratory investigation results were as follows: hemoglobin, 8.8 g/dL; WBCs, 1,800/cu mm; platelet count, 150,000/cu