Parry-Romberg syndrome is a rare craniofacial disorder characterized by progressive hemifacial atrophy with systematic manifestations. The combination with hemimasticatory spasm is rare, with only 9 patients reported before. In this study, a study of a young male patient with Parry-Romberg syndrome and hemimasticatory spasm on his left side was presented. Radiologic examinations showed severe atrophy limited to subcutaneous tissue and electromyography demonstrated as hemimasticatory spasm. Injection of botulinum toxin type A was applied for the treatment of hemimasticatory spasm and after 2 separated injections, the patient was significantly relieved from symptom. The theory of focal demyelination of the trigeminal nerve peripheral brunches is the possible link between hemifacial atrophy and hemimasticatory spasm, although the pathogenesis of both diseases requires further study and current therapeutic methods are still limited to symptomatic treatments. Injection of botulinum toxin type A is an effective way to treat hemimasticatory spasm and autologous fat transplant is a promising solution to correct facial asymmetry.