We describe a successful treatment of 28-year old man who ingested in a suicidal attempt up to 30 pills each containing 150 mg (4500 mg) of propafenone. Results of clinical toxicology were obtained with high performance liquid chromatography from the urine sample. Semiquantitative analysis has shown a high peak for propafenone hydrochloride. The main clinical findings were coma, hypotension, acidosis, sinoatrial block, junctional tachycardia and ventricular arrhythmias necessitating defibrillation. Maximum occurence of arrhythmias was observed 2.5 hours after hospital admission, while the cessation of toxic signs started 4.5 hours later. Gastric lavage, arteficial ventilation, administration of alkalinization solutions and management of rhythm disorders were the most important therapeutic measures in this case. (Fig. 2, Ref. 18.)