Objectives: Experiences of discrimination at work are a long-standing problem, but research on its mental health effect is sparse. The purpose of this study was to examine the prospective association between workplace discrimination and onset of depressive disorders among Danish workers.Methods: The prospective cohort study comprised 2157 workers, all free of depressive disorders at baseline. Using logistic regression models, we estimated the association between workplace discrimination at baseline and depressive disorders at 6-months follow-up, adjusted for demographics, health behaviors, job group, educational attainment and other psychosocial working conditions.Results: At baseline, 103 participants (4.8 %) reported workplace discrimination during the previous 12 months. Among the 103 exposed participants and the remaining 2054 unexposed participants, onset of depressive dis-orders during follow-up occurred in 16 (15.5 %) and 88 (4.3 %) participants, respectively. After adjustment for all covariates, the odds ratio was 2.73 (95 % confidence interval: 1.38-5.40) comparing exposed to unexposed participants. Limitations: All measures were self-reported, entailing risk of common methods bias, and we also cannot rule out selection bias.Conclusions: Exposure to workplace discrimination is a risk factor for onset of depressive disorders. Eliminating or reducing workplace discrimination may contribute to the prevention of depressive disorders in working populations.