Endurance training has a documented effect on hypertension. However, only low to moderate training intensity has so far been studied. High aerobic intensity should, from physiological considerations, prove more effective in also reducing high blood pressure. The present study is a randomised comparison of high versus moderate intensity versus training in groups, and general advice on 24 hour blood pressure in hypertensives. The training period is 12 weeks, with follow-up after 1 year. Maximum oxygen uptake, quality of life, left ventricular function and blood vessel reactivity are also measured.