Photoprotective cosmetic/dermatological compositions well suited for the UV-photoprotection of human skin and/or hair, comprise (a) at least one organic UV-screening agent and (b) an SPF-improving amount of at least one amphiphilic polymerizate of at least one ethylenically unsaturated monomer which comprises a sulfonic group, whether in the free acid or in partially or totally neutralized state, and which amphiphilic polymerizate also comprises at least one hydrophobic moiety.