To confirm the usefulness of head-up tilt test (HUT) in neurocardiogenic syncope (NCS) with complicating clinical features, retrospective analysis were done on 12 selected children. The age at onset was 12.7 +/- 1.9 (mean +/- SD) years. Associated clinical features were postoperative congenital heart disease (PO CHD) in 3, coexistent arrhythmia in 8 (persistent ventricular arrhythmia during exercise in 3, premature ventricular contractions in 2, ventricular couplets in 1, sinoatrial exit block in 1 and resting sinus bradycardia in 1) and ST segment depression during exercise in 1. Four of them had a history of exercise-related syncope. All 3 patients with PO CHD had arrhythmia (ventricular tachycardia in 1, sinus bradycardia in 1 and atrioventricular block in 1). HUT provoked NCS in 8 (2 during baseline tilt, 6 during isoproterenol infusion). In one each, ventricular tachycardia and loss of consciousness without hypotension and bradycardia were induced. Atenolol was tried in 5 with improvement of NCS in 4 and aggravation of dizziness in 1. During follow-up, 7 became asymptomatic (2 with atenolol) and 5 were stationary. In conclusion, HUT was valuable in diagnosing NCS even in children with complicating clinical features such as arrhythmias or PO CHD. HUT could be done as apart of initial diagnostic tests if the past history suggests NCS, regardless of associated clinical features. In some cases, the unexpected results of the test turned out useful in managing children with syncope or dizziness.