Cyanosis as a result of right-to-left shunting across a ventricular septal defect is commonly encountered in patients with congenital heart disease when systolic pressure in the right ventricle exceeds that in the left ventricle. Reported is the case of a child who remained cyanosed after surgical correction of pulmonary atresia despite right ventricular systolic pressure being lower than left ventricular pressure. Colour-flow Doppler showed a residual ventricular septal defect, with right-to-left shunting in diastole alone.