Glufosinate is a non-selective herbicide widely used in domestic gardens and agriculture. Few cases of glufosinate poisoning have been reported although there has been an increase in recent years, particularly in Japan. Glufosinate toxicity is related to its capacity to inhibit glutamine synthetase and glutamate decarboxylase, which may lead to a potentially fatal multiorgan failure. We report the case of a 41-year-old woman who ingested between 30 and 50 mL of a herbicide (Finale) containing glufosinate (14%) in a suicide attempt. One hour after ingestion, the patient attended the Emergency Department of her own volition. Her overall status was good, and the physical examination was unremarkable. Gastric lavage was carried out, 25 g of activated charcoal was administered, and the patient was admitted for observation. Seventeen hours later, the patient presented drowsiness and a sinus bradycardia of 40 bpm. Thirty-two hours after ingestion, the Glasgow Coma Score was 8, and orotracheal intubation and mechanical ventilation were begun. At 3 days, the patient presented a self-limiting episode of ventricular tachycardia. She recovered consciousness progressively and was extubated without complications. The evolution was favorable, but the sinus bradycardia persisted up to 8 days after the ingestion. A study of lymphocyte mitochondrial function showed no alteration in mitochondrial oxidative capacity or the enzymatic activity of the complexes of the electron transport chain. A small ingestion of glufosinate can cause severe poisoning, whose manifestations predominantly involve the central nervous system and heart rhythm. Signs and symptoms may not appear for several hours and may persist for several days. In spite of these multi-organ manifestations, no alteration in lymphocyte mitochondrial function has been reported.