This report describes a male infant who developed right upper limb palsy 5 days after birth and contralateral paralysis at 14 days. Abnormal in utero posture of the right arm had resulted in a difficult cephalic delivery. Right shoulder osteomyelitis was diagnosed at age 16 days from clinical, hematologic, and radiologic findings. Antibiotics were administered, followed by complete resolution of the symptoms in 2 weeks. Electromyographic and nerve conduction studies demonstrated direct involvement of the right brachial plexus, secondary to the osteomyelitis, explaining the unilateral onset and the persistent neurogenic pattern involving the muscles innervated by the right posterior branch to the brachial plexus. However, somatosensory evoked potentials indicated damage to the cervical spinal cord likely related to the birth trauma, which in all likelihood was the cause of the left limb palsy and contributed to the right limb picture.