The invention relates to a method of preparing oligorhamnosides, comprising a one-pot reaction in acetonitrile without any rhamnose protection or deprotection reaction. The invention also relates to a composition a mixture of oligorhamnosides, which can be obtained using said method and which has between 2 and 12 rhamnose units. The invention further relates to a medicament comprising said composition, which is preferably intended to regulate inflammatory mechanisms, and to a cosmetic treatment method.