Although primary cardiac tumors are extremely rare, their prenatal and neonatal management is very important because fetal arrhythmia is a frequent complication and such tumors may be the only manifestation of tuberous sclerosis. We present 2 cases of fetal cardiac tumor in which cardiac function was assessed by color Doppler ultrasonography. In both cases, there was no evidence of tuberous sclerosis or cardiac failure and tumor regression was noted 8 months after birth. Ultrasonographic examination of fetal cardiac function was useful in the management of these tumors.