Terminal transverse limb defects rarely are reported as familial. Multiple pathogenetic mechanisms, including vascular disruption, have been proposed to account for these defects. We report on a family followed over the past 6 years known to have familial cavernous angiomatosis in which 2 relatives have similar terminal transverse defects at the mid-forearm. Multiple relatives have had episodic bleeding from intracranial cavernous angiomas, a distinct finding in this disorder. Other findings in this family include retinal cavernous angiomas (2 patients), a high incidence of skin angiomas (12 patients), cavernous angiomas of the soft tissue (2 patients), and a hepatic angioma (one patient). One of the 2 individuals with the limb defect was evaluated extensively. Magnetic resonance imaging of the forearm with the terminal transverse defect using gadolinium-DTPA enhancement showed abrupt termination of all structures distal to the normal radial and ulnar heads. We propose that familial cavernous angiomatosis may be a new cause of vascular disruption resulting in terminal transverse limb defects.