The long QT syndrome (LQTS) is a genetically transmitted cardiac arrhythmia due to ion channel protein abnormalities, which affects the transport of potassium and sodium ions across the cell membrane. Patients with LQTS may present with syncope, seizures or aborted cardiac arrest. LQTS is also an important cause of unexplained sudden cardiac death in the young. The diagnosis of LQTS is generally made on an ECG showing the prolonged QT interval. The establishment of LQTS registry and the discovery of genetic mutations causing LQTS have contributed greatly to the understanding of this condition and have also provided an impetus in understanding of other inherited cardiac arrhythmias. Genotype-phenotype correlation studies have allowed risk stratification of LQTS patients. Life style modification to avoid triggers for malignant cardiac arrhythmias, and the use of beta-blockers, pacemakers and implantable defibrillators, help to treat symptoms and reduce mortality in these patients.