BACKGROUND: Deep Hypothermic circulatory Arrest (DHCA) is widely used during heart surgery in neonates and infants and complicated surgeries in adults such as a pulmonary thromboendarterectomy (PTE). However safe limits of time and temperature during DHCA still remain controversial. Futhermore it's effects on neurologic outcome has been controversial. METHODS: On the postoperative 3 days, we examined the neurologic function of 12 patients who received a PTE. During the PTE, DHCA was done 2 or 3 times within 20 minutes. Between DHCAs the patients were perfused at a low flow rate with 18degreesC blood until their venous saturation returned to 90%. Neurologic evaluations included level of consciousness, Glasgow coma scale (GCS), and motor and sensory functions. RESULTS: Neurologic functions of all of the patients assessed on the 3 days postoperatively was grossly normal. All 12 patients were oriented to time, place, and person with normal gross motor and sensory functions. CONCLUSIONS: No significant neurologic complications were related to the technique of two or three times of short DHCA within 20 minutes, for a total not exceeding 60 minutes.