Focal dystonia of musicians is one of the most disabling problems for professional musicians. It has focal task-specificity, presenting with involuntary flexion or extension of individual fingers when musicians play their instruments. It occurs mostly in pianists, and controversies still exist about the pathophysiology, whether it is caused by motor function disability or by a psychological condition. Although sensorimotor rehabilitation, change in instrument, skill or teacher, and immobilization with brace have been tried as treatment, there is still no definitive treatment. Because botox therapy has been effective in certain cases without irreversible side effects, this could be applied even in professional players. We report a case of focal dystonia of the hand in a professional pianist treated using electromyogram-guided botox injection and a review of the relevant medical literature.