The invention relates to the fields of immunology and vaccinology. Provided is a method for preparing adjuvanted virosomes, comprising the steps of: (i) providing an aqueous composition of non-adjuvanted virosomes comprising a membrane fusion protein (ii) dissolving an amphiphilic adjuvant in a pharmaceutically acceptable non-aqueous solvent which can form a homogeneous mixture with water and (iii) diluting said adjuvant solution in said aqueous virosome composition to induce insertion of adjuvant in the outer leaflet of the virosomal membrane while preserving membrane fusion activity of the virosomes. Also provided are adjuvanted virosomes obtainable by said method, and vaccines comprising the virosomes.
