The present invention relates to a composition comprising at least one oxazoline, such as OX100, for inhibiting the growth of Malassezia yeasts and/or for preventing and/or treating conditions caused by Malassezia yeasts, seborrheic dermatitis, cradle cap, Malassezia folliculitis, dandruff, Pityriasis versicolor or Pityriasis capitis. The present invention also relates to a composition comprising at least one oxazoline such as OX100, at least one compound such as malic acid diester and a vegetable oil oleodistillate and/or arabinogalactan, and to the use of same for preventing and/or treating, in particular, affections caused by Malassezia yeasts, seborrheic dermatitis, cradle cap, Malassezia folliculitis, dandruff, Pityriasis versicolor or Pityriasis capitis.