Introduction The Depressive Anxiety and Stress Scale (DASS-21; Antony et al., 1998) had been widely used to measure psychological distress among clinical and non-clinical populations, including in Portugal (Pais-Ribeiro et al., 2004). Although DASS-21 has been considered useful to evaluate psychological distress in the perinatal period, studies reporting on its psychometrics are scarce (Brunton et al., 2015). Objective To investigate the psychometric properties of the DASS-21 in a Portuguese sample of pregnant women. Methods Four hundred and twenty-seven pregnant women (mean age: 32.56 ± 4.785 years) in their second trimester of pregnancy (17.34 ± 4.790 weeks of gestation) completed the Portuguese versions of DASS-21 and of Postpartum Depression Screening Scale (PDSS-24; Pereira et al., 2013). Results The DASS-21 Cronbach's alpha was “very good” (a = 0.92). Following the Kaiser and the Cattel Scree Plot criteria, two factorial structures were explored. Three factors structure (explained variance/EV = 57.18%): F1-stress (included 8 items; α = 0.89); F2-Anxiety (7 items; α = 0.79); F3-Depression (6 items; α = 0.82). In the two factors structure (EV = 50.96), the Stress and Anxiety items load in the same factor (F1: 15 items; α = 0.91) and the F2 is composed of the Depression items (F2: 6 items; α = 0.82). Pearson correlations between DASS-21 total and dimensional scores and the PDSS-24 scores were all significant, positive and moderate to high (@.50). Conclusions The Portuguese version of DASS-21 has good reliability, construct and concurrent validity when used with pregnant women. Its factorial structure significantly overlaps with the original, with only one item loading in another factor. DASS-21 could be very useful in diverse settings in the perinatal period. Disclosure of interest The authors have not supplied their declaration of competing interest.