To investigate changes of electrocardiographic parameters with aging and their relation to the presence of SCN5A mutation in probands with Brugada syndrome (BS), we measured several electrocardiographic parameters prospectively during long-term follow-up (10 +/- 5 years) in 8 BS probands with SCN5A mutation (SCN5A-positive group, all men; age 46 +/- 10 years) and 36 BS probands without SCN5A mutation (SCN5A-negative group, all men; age 46 +/- 13 years). Throughout the follow-up period, depolarization parameters, such as P-wave (lead II), QRS (leads II, V(2), V(5)), S-wave durations (leads II, V(5)), and PQ interval (leads II) were all significantly longer and S-wave amplitude (II, V(5)) was significantly deeper in the SCN5A-positive group than in the SCN5A-negative group. The SCN5A-positive group showed a significantly longer corrected QT interval (lead V(2)) and higher ST amplitude (lead V(2)) than those in the SCN5A-negative group. The depolarization parameters increased with aging during the follow-up period in both groups; however, the PQ interval (lead II) and QRS duration (lead V(2)) were prolonged more prominently and the QRS axis deviated more to the left with aging in the SCN5A-positive group than in the SCN5A-negative group. In conclusion, conduction slowing was more marked and more progressively accentuated in Brugada probands with SCN5A mutation than in those without SCN5A mutation.