Introduction
The Posttraumatic Cognitions Inventory is a largely used measure to assess negative posttraumatic cognitions that are common among individuals with trauma-related disorders. There was a need to have a valid and reliable short form of it in Persian.

Objective
This study aimed to translate the Posttraumatic Cognitions Inventory-9 item (PTCI-9) into Persian, and evaluate its characteristics and psychometric properties.

Methods
This was a cross-sectional psychometric study using the translation and back-translation technique, experts assessed the content validity of the scale. Participants were 207 Iranian individuals recruited from the general population and 151 of them were trauma-exposed. Participants completed the Persian version of the PTCI-9, Beck Depression Inventory (BDI-II), and the WHO Quality of Life (WHO-QOL) scale. The psychometric properties of the Persian version of PTCI-9 were assessed using Exploration and Confirmatory factor analysis methods. Cronbach's α coefficient and Pearson's analysis were calculated, as well.

Results
Factor analyses supported a 3-factor model including the Self, World, and Self-blame subscales. The Cronbach’s alpha of the Persian version of PTCI-9 (α=0.74) and its subscales (0.76, 0.82, 0.78) demonstrated its acceptable reliability. The Persian PTCI-9 also had strong test-retest reliability (r=0.79). The correlation between the Persian version of PTCI-9 and the BDI-II (r=0.60), and WHO-QOL (r=-0.54) indicated the convergent validity of the scale.

Conclusion
The Persian version of PTCI-9 showed acceptable psychometric properties. It is a brief and pragmatic measure that can be used in Iranian trauma-exposed patients for research and clinical purposes.