The effect of the conditions of the formation of liposomal preparations of streptomycin and dihydrostreptomycin on incorporation of the antibiotics into the liposomes was studied. The liposomes were obtained with the detergent (cholate) method modified by the authors. The modification implies preliminary application of a 20 per cent antibiotic buffer solution on columns for gel filtration of a mixed mycellar antibiotic solution (20 per cent). The volume ratio of the preliminary applied buffer solution and the mixed mycellar solution is higher than 4:1. The new procedure is simple, readily reproduced, providing formation of the liposomal preparations characterized by high levels of the antibiotic incorporation (about 300 micrograms per 1 mg of lecithin). The preparations are stable with regard to the antibiotic release. The liposomes do not aggregate on storage for a long period (more than 6 months). The liposomal preparations thus formed may be useful as intravenous dosage forms of the antibiotics.