Hypertension is the leading cause of death worldwide. Globally and locally there has been an increase in hypertension in children, adolescents and young adults <40 years of age. In South Africa, the first decade of the millennium saw a doubling of the prevalence rate among adolescents and young adults aged 15 - 24 years. This increase suggests that an explosion of cerebrovascular disease, cardiovascular disease and chronic kidney disease can be expected in the forthcoming decades. A large part of the increased prevalence can be attributed to lifestyle factors such as diet and physical inactivity, which lead to overweight and obesity. The majority (>90%) of young patients will have essential or primary hypertension, while only a minority (<10%) will have secondary hypertension. We do not recommend an extensive workup for all newly diagnosed young hypertensives, as has been the practice in the past. We propose a rational approach that comprises a history to identify risk factors, an examination that establishes the presence of target-organ damage and identifies clues suggesting secondary hypertension, and a limited set of basic investigations. More specialised tests should be performed only where there is a clinical suspicion that a secondary cause for hypertension exists. There have been no randomised clinical trials on the treatment of hypertension in young patients. Expert opinion advises an initial emphasis on lifestyle modification. This can comprise a diet with reduced salt and refined carbohydrate intake, an exercise programme and management of substance abuse issues. Failure of lifestyle measures or the presence of target-organ damage should prompt the clinician to initiate pharmacotherapy. We recommend referral to a specialist practitioner in cases of resistant hypertension, where there is severe target-organ damage and when a secondary cause is suspected.