Purpose: Childhood trauma in an important public health concern, and there is a need for brief and easily administered assessment tools. The Early Trauma Inventory (ETI) is one such instrument. The aim of this paper is to test the psychometric properties of the Swedish translation of the short, self-rated version (ETISR-SF), and to further validate the instrument.Materials and Methods: In this cross-sectional study, 243 psychiatric patients from an open care unit in Sweden and 56 controls were recruited. Participants were interviewed and thereafter completed the ETISR-SF. Internal consistency was calculated using Cronbach’s alpha, a confirmatory factor analysis (CFA) was performed and goodness-of-fit was determined. Intra Class Correlation (ICC) was used to calculate test-retest reliability. Discriminant validity between groups was gauged using the Mann–Whitney U-test.Results: Cronbach’s alpha varied between 0.55 and 0.76, with higher values in clinical samples than in controls. Of the four domains, general trauma showed a lower alpha than the other domains. The CFA confirmed the four-factor model previously seen and showed good to acceptable fit. The ICC value was 0.93, indicating good test–retest reliability. According to the Mann–Whitney U-test, the non-clinical sample differed significantly from the clinical sample, as did those with PTSD or borderline diagnosis from those without these diagnoses.Conclusions: The Swedish translation of the ETISR-SF was found to have similar psychometric properties as both the original version and translations. ETISR-SF scores could also distinguish between different diagnostic groups associated with various degrees of trauma, which supports its discriminant validity.