Elsewhere in this issue, Lewin and his colleagues have attempted to estimate the prevalence of potentially curable hypertension among the Hypertension Detection and Follow-up Program (HDFP) population.1 The multicentric study, which was not designed for this purpose, used an algorithm for evaluating patients for secondary hypertension based on information commonly accepted when the study was designed 15 years ago. Since the decision to pursue an evaluation for secondary hypertension was left to the judgment of the specific investigator, fewer than half of the 146 HDFP patients judged to have poorly controlled hypertension, a population in which one would expect the prevalence of secondary forms of hypertension to be increased, were evaluated. Nonetheless, the study confirms the generally held impression that secondary forms of hypertension are less common among patients with mild or moderate levels of hypertension than in those in whom hypertension is accelerated or when a population of older