BACKGROUND: There is still controversy about whether transthoracic echocardiography (TTE) can provide reliable estimations of pulmonary artery pressures (PAP). The primary endpoint of this study was to evaluate the correlation between TTE and right heart catheterisation (RHC) in estimating systolic (SPAP) and mean (MPAP) pulmonary artery pressures. METHODS: Between January 2011 and December 2018, 141 consecutive patients (average age 63.6±11.5 years; 84 women) with suspected or confirmed pulmonary hypertension (PH) were enrolled into this retrospective observational monocentric study. All patients underwent TTE and, within 3 hours, RHC. The correlation between TTE and RHC in estimating both SPAP and MPAP was retrospectively determined. RESULTS: Seventeen (17) of the patients were excluded due to insufficient TTE signal quality. Of the remaining 124 patients, 18 had no PH. There was moderate correlation between both SPAP and MPAP estimated by TTE and those assessed by RHC (r=0.65 and r=0.60, respectively). Bland-Altman analysis revealed a bias of -11.9 mmHg (with the 95% limits of agreement ranging -45.4 to +21.5 mmHg) for SPAP estimation and -4.6 mmHg (with the 95% limits of agreement ranging -27.9 to +18.8 mmHg) for MPAP estimation, suggesting a general overestimation of PAP by TTE. The main factors responsible for discrepancies between TTE and RHC were: female gender, arrhythmic cardiac electrical activity, systemic arterial hypertension, and diuretic treatment. CONCLUSIONS: Transthoracic echocardiography frequently overestimated PAP in comparison with RHC, especially in hypertensive women with arrhythmias and under diuretic treatment.