Criss-cross heart is a rare congenital cardiac anomaly characterized by the crossing of two ventricular inflow streams. We have demonstrated the utility of 4-dimensional color Doppler rendering in diagnosing the criss-cross heart in a fetus. Four-dimensional color Doppler rendering can demonstrate the relative direction of intracardiac blood flows and facilitate recognition of the crossover of inflow streams in the same plane, confirming the criss-cross heart diagnosis in the fetus.