Background : In spite of relative high risk of extrapyramidal side effect and tardive dyskinesia, it is common clinical practice to use antipyschotics in treatment of bipolar I disorder. But in Korea, there has been few study about clinical factors related with antipsychotics treatment in bipolar disorder patients. So the author studied about the clinical factors related with antipsychotics treatment in bipolar inpatients focusing on the comparison of risperidone and classical antipsychotics. Method : By reviewing medical record retrospectively, datas about patient-related, illness-related, and treatment-related clinical factors on antipsychotics use were collected. Association between antipsychotics dose and duration and clinical factors were analysed by statistical method. Results : Aggressive behavior was only statistically significant factor associated with antipsychotics use. And in the case of aggression, maintenance dose of risperidone was not changed(p=0.84), but dose of classical antipsychotics was increased significantly(p=0.005). Total hospital days and antipsychotics treatment duration showed no difference between risperidone and classical antipsychotics treatment groups. Conclusion : Clinical factors associated with antipsychotics use was aggressive behavior. In the case of aggression, risperidone required lesser dose increment compared with classical antipsychotics.