AbstractBachground and aim: Subjective Scales are the tools for investigation of a disorder in view of the person who has the disorder. Subjective stuttering scale (SSS) investigate stuttering in three views such as severity, avoidance and locus of control in a unique protocol that can show the need to assessment of extra aspects of stuttering. The aim of the present research was Investigation of reliability and validity of the Farsi version of Subjective Stuttering Scale Questionaire.Method and Materials With the implementation of a pilot study and semi-structured interviews with17 adult who has stuttering formal validity and internal consistency of the scale (Subjective stuttering scale: SSS) was investigated. Then 20 adult who has stuttering complete modified questionnaire with (PSI: perception of stuttering inventory), (locus of control behavior scale: LCB) and calculating the percentage of stuttered speech samples recorded in order to assess the concurrent validity. The findings were analyzed bydescribtive statics, Cronbach's alpha and pearson correlation.Findings the results based on the Cronbach's alpha (α=0/92) showed that are valid.There is a significant correlation between SS% and the first question of SSS (α=0.01, r= 0.67) and also there is a significant correlation between avoidance sub-test of SSS and avoidance subtest of PSI(α= 0.05, r=0.75)but there was not a significant correlation between the locus of control sub-test of SSS and LBC scale (α= 0.15). This version of SSS has properconstruct validity.Conclusion The present research showed that the Farsi version of SSS is a reliable and valid tool for assessment of stuttering in severity, avoidance and locus of control in view of the person who have stuttering.Key words: stuttering, assessment, self assessment, locus of control, avoidance.subjective stuttering scale.