Introduction: The goal of this research was to investigate psychometric properties of the of state and trait forms of positive and negative affect (PANAS).Methods: This study was correlation design. The samples consist of 447 randomly selected students (191 male, 256 female) from Shiraz University. They completed PANAS and anxiety and depression subscales of the SCL-90-R.Results: Factor analysis showed that each of state and trait forms of PANAS have two factors labeled positive and negative effects. In concurrent validity, correlation coefficients of negative factor in the trait form of PANAS with depression and anxiety subscales of the SCL-90-R were 0.67 and 0.56 respectively. Furthermore, correlation coefficients of positive factor in trait form of PANAS with depression and anxiety subscales of the SCL-90-R were -0.32 and -0.40, respectively. As for reliability, Cronbach's alpha coefficients for state and trait forms of PANAS were between 0.82 and 0.88.Conclusion: The state and trait of the PANAS have appropriate reliability and validity and are suitable scales for research and clinical applications.