The purpose of this descriptive research study was to examine the outcome of the Objective Structured Clinical Examination (OSCE) on nursing students' performances in psychiatric nursing area. The participants were 62 of 4th year nursing students in Faculty of Nursing, Ubon Ratchathani University, Thailand. Purposive sampling was employed to recruit participants. The research instruments were 1) the OSCE model, 2) the nursing students' perception questionnaires on psychiatric nursing performances 3) the nursing students' opinion questionnaires on OSCE. Descriptive statistics were used for data analysis. The result revealed that most of nursing students passed the OSCE test. Total 80.65% passed OSCE in the component of therapeutic relationship skill and 91.94% passed the test in the section of mental health problem screening and assessment skill. Nursing students' perception on psychiatric nursing performances had a good level, the highest score was the section of the perception on psychiatric nursing practice (x̄= 3.88 SD = .61). This research showed that the OSCE helped distinguish nursing students' skills such therapeutic relationship skills and mental health screening and assessment skills. Accordingly, educational institutions should promote the use of the OSCE in all practicum subjects. The OSCE assists nursing students to gain self-perception on nursing skills which can lead to the improvement of their nursing performances.