The present application relates to novel oil-in-water emulsions comprising i) at least one specific 1,3,5-triazine derivative and ii) at least one polyalkyl-polyethersiloxane carrying polyoxyalkylene groups grafted onto the main silicone chain; with the proviso that the said emulsions do not comprise cetylstearyltrimethylammonium chloride. Another subject-matter of the present invention is the use of such emulsions in the manufacture of cosmetic or dermatological compositions intended for the photoprotection of the skin and/or hair and/or other keratinous substances against ultraviolet radiation, in particular solar radiation.