In this study, we report the case of a 59-year-old male patient with organophosphate pesticide poisoning. He visited the local emergency medical center after ingesting 250 ml of organophosphate pesticide. The patient's symptoms improved after the initial intravenous infusion of pralidoxime 5 g and atropine 0.5 mg. However, 18 hours after admission, there was a worsening of the symptoms. A high dose of atropine was administered to improve muscarinic symptoms. A total dose of 5091.4 mg of atropine was used for 30 days, and fever and paralytic ileus appeared as side effects of atropine. Anticholinergic symptoms disappeared only after reducing the atropine dose, and the patient was discharged on the 35th day without any neurologic complications.