Although there are many studies reporting correlations between relative body weight and blood pressure, the correlations are generally of low order. Furthermore, these observational studies provide, at best, circumstantial evidence concerning the effect of weight reduction on elevated blood pressure. After outlining key methodologic criteria for testing the hypothesis that weight loss lowers blood pressure among hypertensive obese subjects, this article reviews the best intervention studies that are available. Despite the demonstration in these randomized trials that weight reduction programs can lower weight successfully, the results for blood pressure lowering are in considerable disagreement. Two studies reported significant lowering of both systolic and diastolic blood pressure, one found significant lowering of systolic pressure only, and two failed to find significant differences in either. The definitive study of substantial weight loss among patients receiving no other antihypertensive treatment or standardized medical treatment with long-term follow-up has yet to be done. At best, weight loss offers very limited benefit for overweight hypertensives. At worst, weight loss programs are expensive to run, cause considerable patient discomfort and may delay the implementation of more effective therapy.