Depression is a major burden for the health-care system worldwide. It is important to use standardized and easily applicable tools for large-scale population screening to improve the early detection of depression. The PHQ-9 has been recommended as the best available screening and case-finding instrument based on its brevity and ability to inform the clinicians on both depression severity and diagnostic criteria.To evaluate the reliability and the validity of the Tunisian version of the PHQ-9 in the general population in Tunisia; the Tunisian version of the Hospital anxiety depression scale (HAD) was used as the gold standard for major depression diagnosis.We undertook a cross-sectional, descriptive and analytical study. A total of 134 participants were enrolled. The PHQ-9 was validated against the HAD reference standard.Test-Retest reliability was determined by intraclass correlation. This scale was stable over 2 weeks (ICC=0,97).The Tunisian version of the PHQ-9 has a good internal reliability (Cronbach's alpha = 0.84). As for criterion validity of the PHQ-9, the Pearson's correlation coefficient between the PHQ-9 and HAD was 0.94 and the Spearman's correlation coefficient was 0,81. A cut-off score of 10 had a sensitivity of 86,2 and a specificity of 83,8. The VPP was 0,6 and the VPN was 0,9. The prevalence of depression in ours ample was 13,4%. There were no statistical difference in gender, education and age for the prevalence of depression.The Tunisan version of the PHQ-9 is a valid and reliable casefinding instrument for detecting depression.