New derivatives of 3-benzylidene camphor, process for preparing them and their use as protective agents against UV rays and as medicaments.Derivatives of 3-benzylidene camphor of formula: ##STR1## in which R denotes a hydrogen atom, a methyl or ethyl radical,R' denotes a hydrogen atom, a methyl or ethyl radical,R and R' being unable simultaneously to denote a hydrogen atom,R.sub.1 denotes a --COOR.sub.2, --CONHR.sub.2, --COO.sup.- M.sup.+, --CHO, --CH(OR.sub.4).sub.2 or --CH.sub.2 OR.sub.4 group,R.sub.2 being an alkyl, alkenyl, cycloalkyl or aralkyl radical containing at most 20 carbon atoms, optionally substituted by hydroxy, alkoxy, amine or quaternary ammonium groups,M denoting a hydrogen atom, an alkali metal or a N.sup.+ (R.sub.3).sub.4 group, R.sub.3 being a hydrogen atom or a C.sub.1 to C.sub.4 alkyl or hydroxyalkyl radical,R.sub.4 denoting H, alkyl, cycloalkyl or aralkyl containing at most 20 carbon atoms.Application in cosmetics for protection against UV rays.Therapeutic application for the treatment of dermatological and rheumatic complaints; anti-tumour activity.