Percutaneous cannulation of the internal jugular vein is widely used for central venous cannulations. Horner's syndrome may develop as a rare complication of internal jugular vein cannulation. We presented a 47-year-old female patient who developed Horner's syndrome one day after uncomplicated internal jugular venous cannulation, which was accompanied by miosis, ptosis, and anisocoria. The symptoms improved within a week.