Two neonates with tuberous sclerosis and giant cell astrocytomas diagnosed soon after birth are described. During attempted surgical resection of their tumors, both infants developed refractory intraoperative cardiac arrhythmias and died. At autopsy, both patients had multiple cardiac rhabdomyomas. Subependymal giant cell astrocytomas rarely present in the neonate, but genetic implications and associated cardiac hamartomas warrant special consideration of these connatal tumors. Surgical considerations suggest that an operative approach to these tumors should be delayed beyond the neonatal period.