Strongyloides stercoralis hyperinfection in a malnourished 6-year-old boy was characterized by severe diarrhea, dehydration and marked hypokalemia, followed by acute respiratory failure due to respiratory muscle paralysis, and cardiac arrest. He was resuscitated and maintained with positive pressure ventilation and intravenous infusion of potassium and gluco-saline solution. These measures produced recovery from the respiratory muscle paralysis. Stool examination revealed eggs and numerous larvae of S. stercoralis, and thiabendazole was initiated. He continued to have severe diarrhea and again developed marked hypokalemia with respiratory muscle paralysis, abdominal distention, and cardiac arrhythmias with cardiac arrest episodes. In spite of fluid and electrolyte replacement the patient died.