Sun protection creams based on smectite(S) and mixed-layer (IS) clays in glycerol emulsions were compared to commercial organic creams with respect to UV penetration. For very thin cream films the organic creams were superior while for thicker films the clay creams gave lower UV penetration. The investigated I/S mixed-layer clay gave more effective protection than Fe-poor S-clays because of better particle alignment and thicker particles. The content of iron compounds was found to be of greatest importance as demonstrated by tests with different amounts of Fe2O3.