An accurte echocardiographic (E) method for determination of left ventricular mass (LVM) was derived from systematic analysis of the relationship between the antemortem left ventricular echogram and postmortem anatomic LVM in 34 adults with a wide range of anatomic LVM (101-505 g). No subject had massive myocardial infarction, ventricular aneurysm, severe right ventricular volume overload or hypertrophic cardiography. The best method for LVM-E identified combined cube function geometry with a modified convention for determination of left ventricular internal dimension (LVID), posterior wall thickness (PWT), and interventricular septal thickness (IVST), which excluded the thickness of endocardial echo lines from wall thicknesses and included the thickness of left septal and posterior wall endocardial echo lines in LVID (Penn Convention, P). By this method, anatomic LVM = 1.04 ([LVIDp + PWTp + IVSTp]3--[LVIDp]3) -- 14 g; r = 0.96, SD= 29 g, N= 34. Standard echo measurements gave less accurate results, as did previously reported methods for LVM-E. LVM-Dp is an accurate, widely applicable method for the study of left ventricular hypertrophy.