Objectives. To examine the longitudinal association between cumulative exposure to racial discrimination and changes in the mental health of ethnic minority people.

Methods. We used data from 4 waves (2009–2013) of the UK Household Longitudinal Study, a longitudinal household panel survey of approximately 40 000 households, including an ethnic minority boost sample of approximately 4000 households.

Results. Ethnic minority people who reported exposure to racial discrimination at 1 time point had 12-Item Short Form Health Survey (SF-12) mental component scores 1.93 (95% confidence interval [CI] = −3.31, −0.56) points lower than did those who reported no exposure to racial discrimination, whereas those who had been exposed to 2 or more domains of racial discrimination, at 2 different time points, had SF-12 mental component scores 8.26 (95% CI = −13.33, −3.18) points lower than did those who reported no experiences of racial discrimination. Controlling for racial discrimination and other socioeconomic factors reduced ethnic inequalities in mental health.

Conclusions. Cumulative exposure to racial discrimination has incremental negative long-term effects on the mental health of ethnic minority people in the United Kingdom. Studies that examine exposure to racial discrimination at 1 point in time may underestimate the contribution of racism to poor health.