Background To date there has been no comprehensive review of the association between left ventricular hypertrophy (LVH) at baseline and subsequent adverse clinical events. Methods A total of 20 studies (with 48,545 participants) published between January 1960 and January 2000, identified through MEDLINE and other sources, related baseline electrocardiographic (ECG) or echocardiographic data on LVH to subsequent cardiovascular morbidity and all-cause mortality. Results The prevalence of baseline LVH was higher in echocardiographic studies than in ECG studies (16%-74% vs 1%-44%, respectively). The adjusted risk of future cardiovascular morbidity associated with baseline LVH ranged from 1.5 to 3.5, with a weighted mean risk ratio of 2.3 for all studies combined. The adjusted risk of all-cause mortality associated with baseline LVH ranged from 1.5 to 8.0, with a weighted mean risk ratio of 2.5 for all studies combined. There was a trend toward a worse prognosis among women with baseline LVH compared with men. These findings persisted in the various population and ethnic groups studied. Conclusion With the exception of one study in dialysis patients, LVH consistently predicted high risk, independently of examined covariates, with no clear difference in relation to race, presence or absence of hypertension or coronary disease, or between clinical and epidemiologic samples. These results clarify the strong relation between LVH and adverse outcome and emphasize the clinical importance of its detection. (Am Heart J 2001;141:334-41.)