The Harlequin syndrome is a rare and benign disorder of the sympathetic nerves that is mostly idiopathic. It is characterized by an erythema associated with an intense sweating of one side of the face, and a pallor and anhidrosis of the other side. A complete workup to rule out secondary organic causes should be done properly. The medical or surgical options are only required if the patient is in demand of treatment. Psychological and social impacts of this condition should be considered while consulting patients for treatment options. We report a case of a 24 years old female patient who presented this syndrome during exercise and heat stress. She improved considerably after botulinum toxin injections.