The purpose of this report is to discuss the association of brachial plexus palsy and congenital deformations. We reviewed all charts of patients less than 1 year of age with obstetrical brachial plexus palsy evaluated by one of the authors (IA) between January 1998 and October 2005 at Miami Children’s Hospital Brachial Plexus Center. Of 158 patients with obstetrical brachial plexus palsy, 7 had deformations (4.4%). Deformations were present in 32% of patients delivered by cesarean section, but in only 2% of patients delivered vaginally. The deformations were ipsilateral, involving the chest in two patients, distal arms in two patients, proximal arm in one patient, ear in one patient, and the leg in one patient. All patients with deformations had unilateral Erb’s palsies. None had a history of maternal uterine malformation. Two presumptive mechanisms of injury, one causing the deformation (compressive forces) and one causing brachial plexus palsy at the time of delivery (traction forces), were present in all cases. The higher incidence of deformation in patients with obstetrical brachial plexus palsy born by cesarean sections and the presence of two presumptive mechanisms in all of the cases presented here raises the possibility that fetal deformations are a risk factor for obstetrical brachial plexus palsy.