Natural history of cardiac rhabdomyoma in infancy and childhood. Although spontaneous regression of cardiac rhabdomyoma has been reported, prognosis is still considered to be poor and surgery continues to be indicated. The experience with rhabdomyoma diagnosed in live infants over a 20-year period was reviewed. Diagnosis by angiography or echocardiography was accepted only if multiple tumors were present or if tuberous sclerosis was also diagnosed. Nine patients (3 diagnosed prenatally and the remaining 6 at age less than 8 months) were identified as having a total of 24 tumors. Measurements in 2 planes demonstrated at least some evidence of regression in 24 patients (100%), with 20 of 24 having complete resolution. One patient required delayed surgery for excision of a subaortic ridge that appeared at the site of a resolved tumor. Our findings suggest that pediatric cardiac rhabdomyoma is most often a benign condition in which spontaneous regression is the rule. Surgery is recommended only for patients with refractory dysrhythmias or severe hemodynamic compromise. 