OBJECTIVE To evaluate the cardiovascular effects of carbamazepine in patients presenting to the emergency department. METHODS A retrospective case series from February 1, 1985, to July 30, 1993. METHODS Six urban EDs. METHODS Seventy-two adult and pediatric patients with serum carbamazepine concentrations greater than 12 micrograms/mL and concurrent 12-lead ECGs. RESULTS The mean carbamazepine level was 24 micrograms/mL (range, 12.6 to 55 micrograms/mL). Minor ECG abnormalities were noted but no clinically significant arrhythmias were found. No correlation was found between carbamazepine concentration and heart rate or PR, QRS, or corrected QT intervals. Four adult patients had transient hypotension. CONCLUSIONS Clinically significant cardiovascular toxicity occurs rarely in patients with toxic carbamazepine concentrations. ECG findings do not correlate with serum carbamazepine concentration.