Rhabdomyoma is the most common primary cardiac tumor identified in utero and in infancy. Usually it has a benign course, which has prompted an expectant approach to its management. We report herein the cases of three patients who presented prenatally with cardiac rhabdomyomas. Only one of them had a benign course. The other two patients provided recognizable characteristics of rhabdomyomas with an unfavorable course and demonstrated that fetal rhabdomyomas can have a fatal outcome.