Isolated systolic hypertension (ISHTN) is rapidly rising in prevalence, largely due to the advancing age of the population and it will soon become the most common type of hypertension. Untreated patients with merely borderline ISHTN already have a 50% grater risk for cardiovascular complications. Several studies demonstrated that treating ISHTN is beneficial. However, such treatment could cause a potential harm by further reducing the non-elevated diastolic blood pressure; a theory that underlies the controversial “J curve”. In this review, we summarize the epidemiology and pathogenesis of this disorder according to the latest studies, with special emphasis on when, and to what goal, blood pressure should be lowered, and with which medications.