To compare the hemodynamic effects following a toxic dose of either agent after intravenous injection in swines, as might accidentally occur during regional anesthesia in humans. Large White pigs were anesthetized with thiopental, tracheal intubation was performed and mechanical ventilation was instituted. Hemodynamic variables were recorded with invasive pressure monitoring and pulmonary artery catheterization. After a 30-minute resting period, the animals were randomly divided into two groups in a double-blinded fashion and received a bolus intravenous injection of 4 mg.kg-1 of either agent. Hemodynamic results were evaluated at rest and 1, 5, 10, 15, 20 and 30 minutes after intoxication. Hemodynamic repressions of acute intoxication with levobupivacaine were more important and more prolonged than those of ropivacaína. In pigs, levobupivacaine was shown to be more toxic than ropivacaine when the same large doses are injected intravenously.24296-302