SummaryElectrocardiography (ECG) is used to screen for pulmonary hypertension (PH). However, it is unclear which parameters of ECG are the most useful for screening.ECG parameters related to right ventricular hypertrophy criteria were examined in 145 ECGs of subjects who were suspected to have PH and underwent right heart catheterization (RHC) (age 58.4 ± 17.5 years, 112 women, mean pulmonary arterial pressure [MPAP] 35.4 ± 13.3 mmHg). Based on the results of RHC, 108 subjects had PH (56 pulmonary arterial hypertension [PAH] and 52 chronic thromboembolic pulmonary hypertension [CTEPH]).Fourteen of 17 ECG parameters in the present study were significantly associated with PH on univariate analysis. On multivariable logistic regression analysis, S wave depth in lead V5 (odds ratio [OR] 1.25, 95% confidence interval [CI] 1.10-1.47) and depth of T wave inversion in lead V4 (OR 1.21, 95% CI 1.03-1.46) were independent predictors of MPAP !25 mmHg, and the cut-off values determined by receiver operating characteristic curve analyses were 0.42 mV and -0.28 mV, respectively.In conclusion, a deeper S wave in lead V5 and the presence of a wider extent of negative T waves in the precordial leads may be clinically simple and useful ECG parameters for screening for PH.(Int Heart J 2018; 59: 136-142) Key words: Pulmonary arterial hypertension, Chronic thromboembolic pulmonary hypertension P ulmonary hypertension (PH) causes pressure overload of the right ventricle (RV) with RV hypertrophy and dilatation, leading to right heart failure and premature death. Despite recent advances in management, the prognosis of PH patients is still poor, with a 3-year survival rate of 67%.