The hemodynamic data and electrocardiograms of thirty-three patients of moderate to severe aortic stenosis were analysed retrospectively to find out if there was any correlation between 12 lead ECG-QRS score and left ventricular peak systolic pressure (LVPSP) and/or peak systolic gradient (PSG) across the aortic valve. The mean age of the study population was 33.33 (+/- 15.02SD) years, with the male to female ratio being 9:2. The mean 12 lead ECG-QRS score in these 33 patients was 281 mm (+/- 46.02SD), the mean LVPSP 203.52 mmHg (+/- 46.62SD) and the mean PSG across the aortic valve was 81.0 mmHg (+/- 41.62SD). There was good correlation of 12 lead ECG-QRS score with LVPSP (r = 0.47, P less than 0.001) and with PSG across the aortic valve (r = 0.58, P less than 0.001), latter being more significant. The best correlation was however found between 12 lead ECG-QRS score and PSG across the aortic valve in patients over 35 years of age (r = 0.88). In conclusion there is a direct relationship between 12 lead ECG-QRS score and peak systolic gradient across the aortic valve and the latter can be approximately calculated non-invasively with the help of regression equation- Peak systolic gradient (in mmHg) = 12 lead ECG-QRS score/3 - 10.6