Echocardiography is an invaluable tool aiding the diagnosis, preoperative and postoperative assessments and the follow-up of congenital heart diseases (CHD). Acyanotic CHD is defined as a CHD with normal systemic saturation of >95% at the time of initial diagnosis. Depending on the type of the lesion, degree of physiological disturbance and the natural history, each lesion warrants medical, surgical or transcatheter interventional therapy. This chapter covers the classification of acyanotic CHD, chamber dilatation in atrial septal defect (ASD), pulmonary hypertension in ASD, ostium secundum ASD, sinus venosus ASD, ventricular septal defects, ostium primum ASD, chamber dilatation in VSD, pulmonary hypertension versus pulmonary vascular disease in VSD, perimembranous VSD, patent ductus arteriosus, subvalvular or infundibular stenosis, left ventricular outflow tract obstruction, and supravalvular aortic stenosis.