Background and aims: COVID-19 and low levels of vitamin D appear to disproportionately affect black and minority ethnic individuals. We aimed to establish whether blood 25-hydroxyvitamin D (25(OH)D) concentration was associated with COVID-19 risk, and whether it explained the higher incidence of COVID-19 in black and South Asian people. Methods: UK Biobank recruited 502,624 participants aged 37e73 years between 2006 and 2010. Baseline exposure data, including 25(OH)D concentration and ethnicity, were linked to COVID-19 test results. Univariable and multivariable logistic regression analyses were performed for the association between 25(OH)D and confirmed COVID-19, and the association between ethnicity and both 25(OH)D and COVID19. Results: Complete data were available for 348,598 UK Biobank participants. Of these, 449 had confirmed COVID-19 infection. Vitamin D was associated with COVID-19 infection univariably (OR ¼ 0.99; 95% CI 0.99e0.999; p ¼ 0.013), but not after adjustment for confounders (OR ¼ 1.00; 95% CI ¼ 0.998e1.01; p ¼ 0.208). Ethnicity was associated with COVID-19 infection univariably (blacks versus whites OR ¼ 5.32, 95% CI ¼ 3.68e7.70, p-value<0.001; South Asians versus whites OR ¼ 2.65, 95% CI ¼ 1.65 e4.25, p-value<0.001). Adjustment for 25(OH)D concentration made little difference to the magnitude of the association. Conclusions: Our findings do not support a potential link between vitamin D concentrations and risk of COVID-19 infection, nor that vitamin D concentration may explain ethnic differences in COVID-19 infection.