Objectives:
This study aimed to present the Polish adaptation and preliminary normalization of the Depression Anxiety and Stress Scale – 42 (DASS-42).

Methods:
The study was conducted among 1,021 participants (625 females and 396 males) aged 18–83 years (M = 30.67; SD = 13.25). It was a non-clinical sample. Second sample was a group of 49 psychiatric patients (28 females and 21 males) aged 22–76 years (M = 49.40; SD = 13.34). The reliability of the DASS-42 was measured using Cronbach’s α coefficients and intraclass correlation coefficients (ICC).

Results:
In the non-clinical sample the Cronbach’s alpha coefficient was 0.93 points for the depression subscale; 0.89 points for the anxiety subscale; 0.92 for the stress subscale, and 0.96 for the DASS-42 total score. The ICC were satisfactory, between 0.37 and 0.49 points. Psychiatric patients obtained significantly higher results in all subscales and in a total score of the DASS-42 (p< 0.001) than healthy participants. It is an indicator of good concurrent validity of the method. The effect size of the differences for all questionnaire indicators was large (0.96
Conclusions:
The obtained results confirmed the satisfactory psychometric properties of the Polish version of the DASS-42. This inventory may be useful for screening in non-clinical groups and groups of psychiatric patients.