Clinical and electrophysiologic characteristics of 20 patients (15 males; mean age, 42 +/- 9 years) with Brugada syndrome were studied. Electrocardiographic abnormalities (spontaneous in 6 and provoked in 14) were recognized in 5 symptomatic and 15 asymptomatic patients. Mean PR (188 +/- 18 vs. 184 +/- 24 ms) and QT (362 +/- 34 vs. 382 +/- 28 ms) intervals and ST-segment elevation (2.28 +/- 0.42 vs. 2.70 +/- 0.77 mm) were similar in both groups. The PR interval was slightly longer in males than females (191 +/- 21 vs.168 +/- 18 ms, p = 0.042), but ST-segment elevation (2.70 +/- 0.78 vs. 2.24 +/- 0.26 mm) was similar. The HV interval was longer in males than females (57 +/- 4 vs. 50 +/- 4 ms, p = 0.047). Ventricular arrhythmias were induced in 40% of asymptomatic patients. There was no significant difference in age, sex, PR interval, ST-segment elevation, or HV interval between inducible and non-inducible patients. A defibrillator was implanted in 8 patients. During 16 +/- 2 months of follow-up, one symptomatic patient had appropriate device therapy. None of the asymptomatic and non-inducible patients experienced a cardiac event. Electrophysiologic data have no role in predicting inducibility in programmed stimulation.