An intrapericardial aneurysm of the left atrium in a twenty-eight-year old asymptomatic woman is reported. The aneurysm was diagnosed by two-dimensional echocardiography and the specific intraaneurysmatic flow pattern was described by color blood flow imaging. To the authors' knowledge such a noninvasive diagnosis of a left atrial aneurysm has never been reported in the literature before. The diagnosis was confirmed by angiocardiography. The aneurysm was successfully resected. The patient was discharged without medication and continues to do well.