The present invention relates to the use of at least one caprolactam derivative of formula (I) below: in which: n = 0 or 1 m = 0 or 1 p = 0 to 13 R1 is a linear or branched alkyl radical comprising a number t of carbon atoms of from 1 to 20 subject to the following conditions: (i) when p = 0, m = 0, (ii) when p = 1 and n = 1, m = 1, (iii) when p = 1 and n = 0, m = 0 and R1 denotes a C2-C20 alkyl radical with the proviso that the sum of p + t is between 3 and 20, in a composition comprising, in a cosmetically acceptable medium, at least one liquid fatty phase and at least one lipophilic active agent, and containing no dibenzoylmethane-type UV screening agent, as a solvent for said active agent in said liquid fatty phase and/or as an agent improving the solubility of said active agent in the solid fatty phase. The present invention also relates to a composition comprising, in a cosmetically acceptable medium, at least one liquid fatty phase, characterized in that it comprises at least one caprolactam derivative of formula (I) as defined above and in that it does not contain a dibenzoylmethane-type UV screening agent.La présente invention concerne lutilisation dau moins un dérivé de caprolactame de formule (I) ci-dessous : dans laquelle : n = 0 ou 1 m = 0 ou 1 p = 0 à 13 R1 est un radical alkyle linéaire ou ramifié comprenant un nombre t datomes de carbone de 1 à 20 soumis aux conditions suivantes : (i) lorsque p = 0, m = 0, (ii) lorsque p = 1 et n = 1, m = 1, (iii) lorsque p = 1 et n = 0, m = 0 et R1 désigne un radical alkyle en C2-C20 à condition que la somme de p + t soit comprise entre 3 et 20, dans une composition comprenant, dans un milieu acceptable en cosmétique, au moins une phase grasse liquide et au moins un agent actif lipophile, et ne contenant pas dagent écran anti-UV de type dibenzoylméthane, en tant que solvant pour ledit agent actif dans ladite phase grasse liquide et/ou en tant quagent améliorant la solubilité dudit agent actif dans ladite phase
