Cardiac rhabdomyoma, a rare benign tumor often detected in infancy, is frequently associated with tuberous sclerosis. This association is commonly stated to occur in 50% of all cases of cardiac rhabdomyoma. Recently at our institution, the prenatal detection of a cardiac rhabdomyoma in a fetus at no known risk for tuberous sclerosis emphasized the need to determine the frequency of association in order to provide accurate diagnosis and counseling in such situations. After a review of reported cases and review of patients from our institution diagnosed to have cardiac rhabdomyoma, we estimate that 51–86% of cardiac rhabdomyomas are associated with tuberous sclerosis. We present the results of our literature and case review.