Objectives: The present study was designed to investigate the prevalence of psychiatric disorder in over 15 years old residents of Kermanshah, capital of a western province of Iran. Method: Five hundred and one males and females (270 females and 231 males) throughout random-cluster sampling were investigated by using Self Rating Questionnaire (SRO) and Symptom Check List-90-Revised (SCL-90-R). Results: The findings revealed that 25.2% of the sample suffered from a psychiatric disorder, anxiety disorder (16.6%) and personality disorders (8.6%) were the most common. The prevalence of psychiatric disorders were more common among females (widows and divorced), the elderly, the jobless, illiterates, housewives, families with fewer members and those with family history of a psychiatric disorder. Conclusion: Beyond the above findings, SRO proved to have proper capacity for screening purpose. The test-retest analysis and internal consistency of the questionnaire were satisfactory in these respects .