Objectives : The current research aim was to investigate reliability and validity of Social Phobia Inventory (SPIN) in Ahwaz universities’ students. Method: The sample for current survey included 800 (400 girls and 400 boys) students from Shahid Chamran University, Jondishapoor University of Medical Sciences, Payam-e-Noor University of Ahvaz, and Islamic Azad University Ahvaz Branch who were selected using multistage cluster random sampling method. Data collection was through SPIN. Results: Findings showed that the SPIN measures three dimensions of social phobia including fear, avoidance and physiological sign. The scale validity was examined in two ways of exploratory and confirmatory factor analyses. All items significantly loaded on their related factors. The internal consistency for the whole scale and all three extracted factors were favorable. The within items and with the whole scale correlations were between 0.378 and 0.708 range, and all were significant (p≤0.001). Similar to the main scale, a varimax rotation exploratory factor analysis revealed three factors determining 49.05% of the scale variance. Cronbach’s alpha was 0.869. Based on standard Z score, examinees scores were described under 5 scales of “no clear signs” (percentile score lower than 20), “low” (percentile score 20-40), “moderate” (percentile score 40-70), “high” (percentile score 80-90) and “very high” (higher than 90). Conclusion : The Persian version of SPIN is suitable regarding psychometric properties and could be used as a screening, clinical diagnosis and research instrument.