A 3-month-old girl was presented with a right-sided neck mass present since birth and accompanied by homolateral miosis, ptosis and enophthalmos (Horner's syndrome). Diagnostic work-up revealed an underlying cervical neuroblastoma. Although the association of Horner's syndrome with acquired neuroblastoma is well-known and of value in early diagnosing of such a tumor, it can also be a presenting or accompanying sign in rare cases of congenital neuroblastoma.