In a highly select group of stable hypertensive patients, we have assessed the strength of association between various blood pressure measurements (24 h average automated ambulatory blood pressure, 4 h automated ambulatory morning average blood pressure, multiple office visit average blood pressure, and a single office visit average blood pressure) and various echocardiographic indices of hypertensive cardiac target organ damage (left atrial diameter, left ventricular end diastolic diameter, posterior wall thickness, combined wall thickness, relative wall thickness, left ventricular mass and mass index, and combined wall thickness/left ventricular diastolic diameter ratio). These data demonstrated that a single 24 h average diastolic blood pressure by automatic noninvasive ambulatory monitoring was a significantly better predictor of echocardiographic posterior wall thickness, combined wall thickness or relative wall thickness than the multiple office or single office average diastolic blood pressure. Also there were highly significant correlations between both 24 h average systolic and diastolic blood pressure and these echocardiographic parameters (in descending order of correlation coefficient): combined wall thickness, posterior wall thickness, combined wall thickness/left ventricular diastolic diameter, left ventricular mass index, relative wall thickness, and left ventricular mass. Left ventricular end diastolic dimension did not linearly correlate with any systolic or diastolic blood pressure measurement. Left atrial dimension demonstrated only a significant association with 24 h average diastolic blood pressure. Single office average blood pressure did not linearly correlate with any echocardiographic parameter.(ABSTRACT TRUNCATED AT 250 WORDS)