“Ms. A,” a 35-year-old woman, fulfilled the DSM-IV-TR criteria for schizophrenia, paranoid type. There was no family history of neurological or medical disorders. Her illness began at age 21 years. Her initial symptoms were characterized by auditory hallucinations and persecutory delusion. She had been treated with several antipsychotics, including risperidone, sulpiride, quetiapine, and perospirone. She started receiving perospirone (8 mg) at age 26 years, and had been prescribed perospirone and one/two benzodiazepines since age 27 years. From age 29 years, perospirone dosage was generally 32 mg. After being on this dose for 1½ years, she exhibited cervical dystonia. Perospirone was then decreased (to 12 mg), and biperiden (6 mg) was added. However, since her dystonia was not improved, we additionally prescribed clonazepam (1 mg) and diazepam (4 mg). Consequently, her dystonia disappeared after 1 month. Over the following year, perospirone was increased (to 32 mg), biperiden was decreased (to 2 mg), and clonazepam and diazepam were stopped. After maintaining this dosage for 2 months, she developed symmetrical oromandibular dystonia. Perospirone was decreased (to 24 mg); accordingly, her dystonia was improved, although it did not completely disappear. For the next 2½ years, she showed no relapse of psychotic symptoms and marked side effects during perospirone monotherapy (24 mg; no biperiden). However, she exhibited symmetrical mild oromandibular dystonia and blepharospasm, and had difficulty keeping both eyes open. She had to discontinue vision-dependent tasks like watching TV, cooking, and walking. No abnormal movements were observed in other areas of her body. We added biperiden (3 mg), and these symptoms were almost gone 1 month later. Although her abnormal facial movements did not completely disappear, she showed no difficulties in managing activities of daily living. To date, she has had no exacerbation of psychotic symptoms and remarkable side effects for 1 year with perospirone (24mg) and biperiden (3 mg).