A 15-day-old Holstein calf with lethargy and tachypnea presented to the Veterinary Teaching Hospital at Obihiro University of Agriculture and Veterinary Medicine for evaluation of suspected congenital heart defect. A Levine grade 6 systolic murmur was noted at right apical site auscultation and phonocardiogram also recorded systolic a murmur. Electrocardiography findings include increased R and S waves, R wave split, and negative T waves without arrhythmia. Echocardiography revealed a single ventricle with a trace of the right ventricular wall, atrioventricular valve regurgitation, and turbulent in a single ventricle. Arterial blood analysis showed a marked decrease in oxygen saturation of 78% and oxygen partial pressure of 44 mmHg. Post-mortem examination confirmed the diagnosis of a single left ventricle.