Water intoxication in schizophrenia poses a great clinical challenge, and occasionally, behavioral restrictions are unavoidable. A patient with refractory schizophrenia comorbid with severe water intoxication had an apparent weight variation of ,7 kg/day to 65 kg. As he fell twice, when he had been treated with antipsychotic megadose therapy, he was secluded with restricted water access of 3 L/day. Two days later, consciousness level deteriorated significantly with autonomic instability; however, he was treated with intravenous hydration plus dantrolene and recovered completely on the following day. The sodium/chloride levels and serum osmolarity, which had been abnormally low, normalized abruptly. Only after seclusion was it found that his dry weight had been only 52 kg. The first description of such a case was indicative of a potentially aborted neuroleptic malignant syndrome. He is now treated with olanzapine, valproate, and lorazepam, with some success. Caution is required for secluding extreme cases of uncontrollable water intoxication.