We describe a case of contralateral Horner's syndrome following stellate ganglion block.A 56 years old man diagnosed with complex regional pain syndrome type II in right upper arm, who developed after the application of local anesthetic guided by ultrasound in proximity to the right stellate ganglion presented left Horner's syndrome.The contralateral Horner's syndrome following stellate ganglion block is a rare entity.In our practice occurred one of the few cases reported in the literature, which is of great interest for the medical community.