OBJECTIVE The aorto-left ventricular tunnel (ALVT) is a rare congenital cardiac malformation with clinical findings of severe aortic insufficiency. We report the echocardiographic differentiation of different anatomical variants of ALVT in two infants. RESULTS Echocardiography in both patients demonstrated severe enlargement of the ascending aorta and the left ventricle. In the first patient the ALVT originated from the ascending aorta above the right coronary sinus and entered the left ventricle just below the aortic valve. In the second patient the ALVT originated above the left coronary sinus and took a lateral course to the left ventricle. Colour-Doppler-sonography in both patients confirmed a systolic-diastolic flow across the tunnel. Many patients have associated cardiac defects. Exact determination of the morphology of the aortic valve and coronary arteries is mandatory for surgical repair. Postoperative follow-up studies focus on the function of the aortic valve and the left ventricle. CONCLUSIONS Differentiation of different anatomical variants of ALVT is possible trough echocardiography. Cardiac catheterization is required only in cases with inadequate information about coronary artery anatomy.