The cases of intake of organophosphate pesticides reported in Japan are mainly due to oral ingestion associated with attempted suicides. We report a case of organophosphate pesticide poisoning in which percutaneous absorption was suspected to be the cause. A 61-year-old woman was brought to our hospital because of consciousness disturbance. She was found lethargic, lying in the bathroom, by her husband. She had a significant medical history of hypertension. On admission, her Glasgow coma scale (GCS) score was 14/15. Her vital signs were as follows: body temperature, 35.3°C; blood pressure, 185/102 mmHg; heart rate, 106 /min; and respiratory rate, 23 /min. Her oxygen saturation was 100%. Her pupils were 2 mm in diameter, equal in size, round, and reactive. The rest of the examination was unremarkable. Chest X-ray, head CT, and head MRI were performed, but failed to identify the cause of the consciousness disturbance. Three hours after arrival, her oxygen saturation level had fallen and diaphoresis, miosis, and lacrimation had developed, while she was intubated under sedation. Prior to tracheal intubation, we asked her whether she had taken any organophosphate agent, which she denied. No organophosphate smell was detected from the endotracheal tube. Nine hours after arrival, her cholinesterase level was reported to be 11 IU/l, and we could finally confirm the diagnosis. Pralidoxime and atropine therapy was accordingly started. Seventeen hours after arrival, her family brought bottles of pesticide (smithion^®) to the hospital. It transpired that she had handled this organophosphate pesticide without wearing gloves, and that earlier she had received abrasions to her hands. Therefore, it was assumed that the organophosphate was easily absorbed through her skin. Critical care physicians should bear in mind that whenever they see patients with consciousness disturbance, percutaneously absorbed organophosphate poisoning could be one of the causes.