Despite the public perception that heart disease primarily affects men, as women age, their risk equals and eventually outpaces that of men. Gender-specific differences in cardiovascular diseases have been reported related to onset, diagnosis, therapy, pharmacokinetics, adverse drug reactions, and mortality rates, but most of these differences are unexplained. Research in coronary heart disease has been performed almost exclusively in men, but the findings have been used to set standards for both sexes. Studies suggest a 50% reduction in heart disease risk among women receiving postmenopausal hormone replacement therapy.