When the R-wave in the lateral precordial leads is less than 10 mm the sensitivity of ST depression is very low if 1 mm of ST depression is used as a standard. The corrected ST for R-wave amplitude is arrived at, by simply dividing the ST by the R-wave amplitude. When using 0.1 as a cut of for an abnormal test, the sensitivity is increased markedly, especially in those with R-waves less than 10 mm. When applying this method to patients with tall R-waves, the specificity is increased but as might be expected, the sensitivity is decreased. This type of correction should become standard practice in the future.