Primary cardiac tumors of any type in infancy and childhood are rare, with a prevalence of 0.03%reported in autopsy surveys carried out at children's hospitals. Within the pediatric population,the most common primary tumor involving the heart is rhabdomyoma. These tumors may bedivided into 3 groups: 1) arising in tuberous sclerosis; 2) arising sporadically; or 3) arising in congenital heart disease. Many cardiac rhabdomyomas are asymptomatic and regress early in life without clinically untoward effects. Only a small proportion of these tumors come to the attention of the pediatrician and pathologist when there is obstruction of blood flow, a murmur related to subaortic stenosis, or arrhythmias. Rhabdomyomas may be detected prenatally during ultrasound examination, with one case being diagnosed at 22 weeks gestation. Although it is possible to subdivide the tumors into 3 groups, the association of this entity with tuberous sclerosis is very strong with at least 60 to 85% of children with rhabdomyomas having tuberous sclerosis.