To the Editor:— Reports of patients with acute chloroquine poisoning have pointed out the rapid, sudden collapse with respiratory and cardiac arrest.1This letter describes two patients with similar collapse but with electrocardiographic evidence of persistent, though grossly abnormal, cardiac activity. Case 1.— A 3-year-old boy was first seen with the story that he had taken seven chloroquine phosphate tablets (a total of 1.75 gm) about a half hour previously. He was drowsy and complained of difficulty in seeing. His pulse was 120 beats per minute and there were a few rhonchi in the chest. A stomach tube was immediately passed in a futile attempt to remove part of what was a fatal dose. A small amount of mucus containing a few granules was aspirated. Within five minutes respirations stopped and the pulse and heartbeat could not be detected. Tracheal intubation with oxygen by bag compression and external cardiac