Diastolic heart failure without left ventricular systolic dysfunction comprises 30% to 50% of heart failure in clinical practice, and hypertensive heart disease is a major cause of this type of heart failure. The complication of myocardial fibrosis should be avoided in hypertensive heart disease, because increasing ventricular stiffness caused by myocardial fibrosis leads to the development of diastolic dysfunction of the heart. Diastolic dysfunction in patients with prolonged hypertension is often associated with myocardial fibrosis in addition to muscular hypertrophy as a final feature of hypertensive heart disease. The high risk of developing maladaptive cardiac remodeling during hypertension, and failure of pharmacological treatments to limit or even reverse this progressive stiffening of the myocardium, has led to the study of effects of Pycnogenol, a bioflavonoid-rich pine bark extract, with pleiotropic actions on cardiovascular system. Pycnogenol prevents adverse hypertension-induced myocardial remodeling in mice, through modulation of gene expression and activity of enzyme matrix metalloproteinases and their tissue inhibitors, affecting myocardial collagen degradation rate. Despite the mounting evidence suggesting the anti-remodeling effect of Pycnogenol in animal models, the clinical efficacy of Pycnogenol in hypertension-induced diastolic dysfunction is unreported. This leads to our central hypothesis that Pycnogenol reverses the hypertension-induced cardiac fibrosis and diastolic dysfunction in hypertensive patients. Therefore in this clinical investigation, we will investigate the effects of Pycnogenol in modifying hypertension-induced cardiac fibrosis (by measuring the serum markers of myocardial fibrosis and collagen turnover) and diastolic dysfunction (by transthoracic echocardiogram). We expect to improve diastolic function and ameliorate myocardial fibrosis with the nutritional supplement Pycnogenol, by modulation of MMPs and TIMPs enzyme activities.