BACKGROUND It is commonly believed that the associations of left ventricular mass and cardiovascular morbidity/mortality with blood pressure are stronger for 24-h ambulatory pressure than for conventional clinic or casual pressure. METHODS The investigation comprised a review of relevant studies, with particular emphasis on the characteristics of the conventional blood pressure measurement. RESULTS A review of 21 studies on left ventricular mass, published between 1982 and 1993, showed that the relationship between mass and blood pressure was stronger for ambulatory blood pressure than for clinic blood pressure but that the methodology and conditions of the conventional blood pressure measurements were poorly described or standardized in several reports. Between 1983 and 2001, seven studies showed that ambulatory blood pressure was superior to conventional blood pressure with regard to the prediction of cardiovascular morbidity and/or mortality. From published data and requests for additional information, it appears that recommendations for the measurement of conventional blood pressure have been reasonably well observed, although the number of measurements has not always been adequate. CONCLUSIONS Whereas the quality of the conventional blood pressure measurements left much to be desired in the studies on left ventricular mass, the quality appeared to be reasonably good in outcome studies, even though the published details were often incomplete.