Left ventricular hypertrophy in systemic arterial hypertension is associated with an increased risk of morbidity and mortality due to cardiovascular disease. Therefore, the diagnosis of left ventricular hypertrophy is clinically important. In current clinical practice, echocardiography is the method of choice for diagnosing left ventricular hypertrophy. This review describes current, clinically applied techniques of measuring left ventricular mass using M-mode and two-dimensional echocardiography. Using M-mode techniques, left ventricular hypertrophy is usually present when myocardial mass estimates exceed 150 g/m2 in males and 120 g/m2 in females. Using two-dimensional echocardiography, upper limits of normal have been described to be slightly lower (102 g/m2 in males and 88 g/m2 in females). In serial clinical two-dimensional echocardiographic studies, image acquisition and quantitation predominantly determine total variability in left ventricular mass estimates. Using any single technician and any single reader, left ventricular mass estimates in normal subjects may vary by 35 g (standard deviation) between serial studies. Strategies to reduce the magnitude of this variability include increasing the number of technicians and readers acquiring and analyzing a single study.