Carotenoids are among the best known antioxidant phytochemicals, and are widely believed to contribute to the health-promoting properties of fruits and vegetables. Investigations of the effects of carotenoids have been carried out at different levels: in cultured cells, in experimental animals, and in humans. Studying reports from the last 5 years, we find a clear distinction between effects of vitamin A and pro-vitamin A carotenoids (the carotenes and β-cryptoxanthin), and effects of non-vitamin A carotenoids (lycopene, lutein, astaxanthin and zeaxanthin). Whereas the latter group are almost invariably reported to protect against DNA damage, whether endogenous or induced by exogenous agents, the provitamin A carotenoids show a more varied spectrum of effects, sometimes protecting and sometimes enhancing DNA damage. The tendency to exacerbate damage is seen mainly at high concentrations, and might be accounted for by pro-oxidant actions of these carotenoids.