Report on a newborn with left-sided radial paresis due to a solitary angioleiomyoma in the lateral distal third of the upper arm. The literature does not disclose that this rare benign tumor can produce radial palsy. A palpable soft-part tumor in the new born suggests malignancy. The tumor including the atrophic radial nerve was radically excised. When histology proved it to be benign, a nerve graft with the sural nerve was carried out. After 6 months of electrical and physiotherapeutic treatment partial radial function had returned. In differential diagnosis of radial palsy of the neonate, birthtrauma is a likely cause. Tumors as a cause are rare and are found almost exclusively in adults, due to lipoma, neuroma or ganglia. In the neonate the socalled "idiopathic" radial paresis does not occur and in adults is usually due to the "supinator syndrome".