Objective To investigate the pulmonary venous flow pattern (PVFP) in atrial septal defect (ASD) and mitral stenosis (MS),to analyze the differences of PVFP in each group and evaluate their clinical value. Methods The characteristics of PVFP and mitral valve flow pattern in 42 patients of ASD and 17 patients of MS were prospectively compared by transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), and also compared with the normal subject. Result The PVFP was significantly different between MS and ASD, including S、D、Ar、S-T (P