Abstract: Risperidone is one of a new generation of antipsychotic drugs with relatively fewer side effects and better efficacy. Our objects were study of relationship between the incidence of Iranian produced risperidone Extrapyramidal Side Effects (EPSE) and its relationship with age, sex, dosage and duration of treatment in patients with schizophrenia or schizoaffective disorders. One-hundred patients with schizophrenia or schizoaffective disorders admitted in Razi hospital of Tabriz, which underwent treatment with risperidone were selected by convenience method and the incidence of EPSE was evaluated for 6 weeks; the results were analyzed statistically. Seventy-two percent of patients showed no complications and 28% of them affected by EPSE. The incidence of complications was not related significantly with age and sex of patients but there was significant relationship between the duration of medication and dosage of drug (pv<0.05). The most EPSE were rigidity, tremor and bradykynesia, but there were not any acute dystonic reaction. Risperidone is one of the new generation antipsychotic drugs with lower side effects and its EPSE are dose-dependent. It is recommended that the treatment be initiated with minimum effective dose.