Background: Pulmonary vein isolation(PVI) is an effective curative procedure for patients with atrial fibrillation(AF). PV stenosis is a potential complication and may be often underrecognized. However, the mechanism and time course of PV stenosis are not completely understood. The aim of this study was to evaluate the change of pulmonary venous flow(PVF) using TTE before and after PV isolation. Methods: 21 patients (M:F=10:11, age 56.4짹9.7yrs, paroxysmal:persistant AF=17:4) were enrolled. PVF was estimated during systole and early diastole in right pulmonary vein(RPV) and left pulmonary vein(LPV) using TTE before and after PVI. In 2 patients showing PVF100cm/s after PVI, osteal-diameter(OD) of 4-PV was estimated by MRI. Results: No patient developed symptom due to PV stenosis. The mean peak systolic flow velocity of RPV was 45.5짹30.8cm/s and 72.9짹38.9cm/s before and after PVI(p=0.003) and the mean diastolic flow velocity of RPV was 38.4짹26.5cm/s and 50.0짹35cm/s before after PVI(p=0.148). The mean peak systolic flow velocity of LPV was 44.5짹34.5cm/s and 50.0짹35.1cm/s before and after PVI(p=0.324) and the mean diastolic flow velocity of LPV was 40.0짹31.7cm/s and 47.0짹28.1cm/s before after PVI(p=0.269). Two patients showing high PVF=118cm/s, PVF=133cm/s on TTE after PVI showed max.PV stenosis=62.5%, 50.0% on MRI, each other. Conclusions: We suggest PV stenosis after PVI could be detected on TTE. The assessment of PVF using TTE might be a useful screening test for the evaluation of PV stenosis.