Horner's syndrome (HS) is related to an interruption of the oculosympathetic 
nerve pathway. The classic clinical findings associated with this condition are 
ptosis, miosis, and enophthalmos. Heterochromia is typically described in 
congenital HS, but it is an uncommon finding in acquired HS. We report a case of 
post-traumatic HS associated with heterochromia. A literature review indicates 
that this type of heterochromia may be related to a reduction in the number of 
iris melanocytes. This mechanism may be the same in the physiological iris color 
modifications in adulthood.