We encountered three cases of organophosphate poisoning treated with pralidoxime iodide (PAM) and whole-bowel irrigation without atropine sulfate. All patients recovered without persistence or recurrence of toxic symptoms and without any somatic after effects. In case 1, a 48-year-old woman ingested approximately 5 g of ethylthiometon in a suicide attempt. She was transferred to the hospital because of cardiopulmonary arrest. After resuscitation, she was transferred to our center. She was placed on a ventilator and received i.v. PAM and polyethylene glycol-electrolyte through a nasojejunal tube for whole-bowel irrigation. Six days later, serum ChE was improved. In case 2, a 51-year-old man ingested approximately 30 g of malathion in a suicide attempt and was transferred to our center because of dyspnea. He was treated with PAM and whole-bowel irrigation, but did not require a respirator. Serum ChE already showed improvement the following day. In case 3, a 31-year-old man ingested approximately 50 g of DEP in a suicide attempt and was transferred to our center because of unconsciousness. He was treated with a respirator, PAM and whole-bowel irrigation. Serum ChE improved within two days. These cases suggest the possibility that preferential whole-bowel irrigation without atropine sulfate prevents the persistence or recurrence of the toxic effects of organophosphate.