Background: Asymmetrical activation of brain hemisphere has been one of the dominant factors that involved in the etiology of psychiatric disorders. The aim of this study is assessment the defected lateralization of the brain`s hemispheres in psychiatric inpatient. Also in this study, the dominance in eye, foot, and hand in healthy and psychiatric inpatient has been compared. Materials and methods: Totally, 113 pre-university students (65 males and 48 females) and 83 psychiatric inpatients (57 males and 26 females) were selected with purposive sampling. We have used psychiatric diagnostic interview and long form MMPI-II test and Millon-III test to detecting mental disorders and screening healthy persons. Edinburg`s hand dominance test and chapman`s foot dominance has been used. Also the scientific method of watching through a hole is used in order to determining the dominance of eyes. Results: The comparing of limb dominance in healthy samples and psychiatric inpatients showed that there was a significance difference of brain asymmetrical activity between healthy samples and psychiatric inpatients regarding their eye dominance (P=0.01). It was determined that left eye dominance in psychiatric inpatients was more common. However, no significant difference was found in hand and foot between two groups. Conclusion: Our findings proved that left eye dominance is more common in psychiatric inpatient.