Botulinum A toxin is used intramuscularly in the treatment of spastic neuromuscular disorders, strabismus, and laryngeal dystonia. The toxin has recently been reported as being useful for the cosmetic removal of glabellar furrows. The clinical effect of the toxin lasts four months or longer. Systemic side effects are rare and usually transient. We report the case of a psoriasiform eruption temporally related to the injection of botulinum A toxin into the medial rectus muscle to treat an ocular motility disorder. To our knowledge, this is the first case of a psoriasiform dermatitis caused by this agent.