To review published literature on the relationship between systolic blood pressure and risk of cardiovascular and renal disease. identification Studies were retrieved using the MEDLINE database, bibliographies, and the authors' reference files. Prospective cohort studies and randomized controlled trials which were published in English-language journals. All retrieved publications were reviewed by the two authors. Information on sample size, duration, study design, antihypertensive medication, participant characteristics and outcomes was abstracted for randomized controlled trials which reported reductions in systolic blood pressure during intervention. Results from several prospective cohort studies indicate that the association between systolic blood pressure and risk of coronary heart disease, stroke and end-stage renal disease is continuous, graded, and independent. Furthermore, they suggest that the association of systolic blood pressure with these outcomes is stronger than that of diastolic blood pressure. Pooling of the data available from randomized controlled trials indicates that an average reduction of 12-13 mmHg in systolic blood pressure over 4 years of follow-up is associated with a 21% reduction in coronary heart disease, a 37% reduction in stroke, a 25% reduction in total cardiovascular mortality, and a 13% reduction in all-cause mortality. Observational epidemiologic studies and randomized controlled trials have demonstrated that systolic blood pressure is an independent and strong predictor of risk of cardiovascular and renal disease.