The diagnosis of sinus-node dysfunction is primarily based on electrocardiographic findings. Sinus-node disease is characterized by arrhythmia and by symptoms. Symptoms such as syncope, light-headedness, dizziness and reduced exercise tolerance due to chronotropic incompetence are manifestations of pathological heart rate control that should disqualify from aircrew licensing. Sinus bradycardia beyond the defined normal range and sinus pauses can be observed also in asymptomatic patients but warrant further investigation including exercise electrocardiography (to maximal heart rate) and Holter monitoring (to exclude subclinical pauses longer than 3 s, inappropriate bradycardia less than 30 beats . min-1, or paroxysmal atrial fibrillation). Even in the absence of such arrhythmias unrestricted licensing may be limited. When electrocardiographic abnormality raises a suspicion of sinus node disease, although test results are normal, repeated annual investigations are recommended for continued re-licensing which may need to be restricted to multi-crew operation.