Self-rating Anxiety Scale (SAS), introduced by Zung, has been widely used in research and in clinical practice for the detection of anxiety. The present study aims at standardizing the Greek version of SAS. SAS consists of 20 items rated on a 1-4 likert type scale. The total SAS score may vary from 20 (no anxiety at all) to 80 (severe anxiety). Two hundred and fifty four participants (114 male and 140 female), psychiatric patients, physically ill and general population individuals, aged 45.40±11.35 years, completed the following: (a) a demographic characteristics' questionnaire, (b) the SAS Greek version, (c) the Spielberg's Modified Greek State-Trait Anxiety Scale (STAI-Gr.-X) and (d) the Zung Depression Rating Scale (ZDRS). Seventy six participants answered the SAS twice within a 12th-day median period of time. The following parameters were calculated: (a) internal consistency of the SAS in terms of Cronbach's α co-efficient, (b) its test-retest reliability in terms of the Intraclass Correlation Coefficient (ICC) and (c) its concurrent and convergent validities through its score's Spearman's rho correlations with both the state and trait subscales of STAI-Gr X and the ZDRS. In addition, in order to evaluate SAS' discriminant validity, the scale's scores of the three groups of participants (psychiatric patients, physically ill and general population individuals) were compared among each other, in terms of Kruskall Wallis and Mann Whitney U tests. SAS Cronbach's alpha equals 0.897 while ICC regarding its test-retest reliability equals 0.913. Spearman's rho concerning validity: (a) when SAS is compared to STAI-Gr.-X (state), equals it 0.767, (b) when SAS is compared to STAI-Gr. X (trait), it equals 0.802 and (c) when SAS is compared to ZDRS, it equals 0.835. The mentally ill scored significantly higher in SAS compared to both the healthy and the general population. In conclusion, the SAS Greek version presents very satisfactory psychometric properties regarding its reliability and validity as well.