Serious adverse reactions to ropivacaine and lidocaine are rare. In this report, we describe a case of sudden cardiac arrest after an interscalene brachial plexus block with a mixture of 150 mg of ropivacaine and 360 mg of lidocaine in a previously healthy, 34-year-old, 97-kg man. Severe hypotension occurred after successful resuscitation, necessitating an infusion of epinephrine. The patient developed pulmonary oedema, and was mechanically ventilated for 22 h. He eventually made a good recovery. We conclude that although ropivacaine and lidocaine are often considered relatively safe local anesthetics, serious cardiovascular complications can occur after the use of these drugs.