The aim of the study was to clarify the feasibility of physical training for middle-aged borderline-hypertensive males. Blood pressure of 59 subjects was followed for nine months, whereafter 25 persons were classified as borderline-hypertensive and 34 persons as normotensive. Both groups were randomly allocated into training and control groups. Training lasted for four months, of which the first two included supervised bicycle ergometer exercise. During the last two months training was unsupervised. After training estimated maximal oxygen consumption increased significantly both in borderline-hypertensive and normotensive men. After training resting diastolic blood pressure decreased significantly both in training and control groups. This finding supports the importance of sufficiently long follow-up of blood pressure before eventual drug therapy when blood pressure is mildly elevated. Diastolic blood pressure during 50-minute ergometer exercise was decreased after four months of training in borderline-hypertensives and did not any longer differ from that of normotensives. Individually prescribed physical training is worth regarding as one treatment modality for middle-aged borderline-hypertensive patients.