Objectives: Visualization of the left atrial appendage(LAA) by the transesophageal echocardiography(TEE) is excellent, but it is difficult to visualize the LAA by the modified parasternal short-axis view(MPSA) in transthoracic echocardiography(TTE). We studied to determine the usefulness of the apical horizontal view(AHV) abtained by the apical rotation method of the transducer for the detection of the LAA. Methods: We studied the MPSA and AHV in 602 patients, The LAA was observed during diastole of the LAA. We obtained an apical horizontal view by 45 degree clockwise rotation of the transducer from the apical 2 chamber view and compared with the visualization of the LAA in AHV and MPSA. Results: Among 602 patients, LAA could not be visualized in 88(14.6%) because of a poor echo-window. LAA was more clearly visualized in 222 patients by the AHV than the MPSA and 56 patients by the MPSA than the AHV. LAA was same degree visualization in patients by the AHV and MPSA. In male and female, more than 55 ages and less than 55 ages, visualization of inner margin of the LAA by the AHV was more clear than by the MPSA. Conclusion: The AHV was a useful, noninvasive and reproducible method for the visualization of the LAA.