The assembly of electron dense ferritin modified by acylation with steaorylchloride into small and large egg lecithin vesicles is reported. From electron micrographs conclusions are drawn: on the mode of ferritin incorporation in the lipid bilayer: Small liposomes seem to be only in superficial contact with the modified protein shell of the ferritin molecule whereas in the larger lipid vesicle type the incorporation is more integral.