Patients suffering from Kearns-Sayre syndrome (KSS) often develop conduction defects that may lead to syncope or sudden cardiac death. The association of conduction abnormalities with prolonged QT interval in these patients is very rare. We describe a patient with KSS and diabetes mellitus who suffered a torsades de pointes-induced syncopal attack, in the presence of trifascicular block and QT prolongation (QTc: 574 ms). The patient was successfully treated with permanent pacing. This case highlights that torsades de pointes represents a potential mechanism of syncope or sudden cardiac death in patients with KSS.