The chemotherapeutic efficacy of streptomycin incorporated into liposomes was studied on mice with experimental tuberculosis. Streptomycin incorporated into liposomes was prepared with the detergent method using purified egg lecithin, sodium cholate and streptomycin sulfate. The level of streptomycin incorporation into liposomes was 250-399 micrograms of streptomycin base per 1 mg lecithin. The size of the liposome was determined by electron microscopy. It was 40-80 nm. BALB/c and (CBA X C57B1(6)) F1 mice infected with M. tuberculosis H37Rv (0.1 mg of half-moist mass per mouse, intravenously) were used in the experiments. It was shown that the liposome-incorporated streptomycin injected intravenously on the 3rd or the 4th day (20 or 25 mg/kg) or 3 times on the 4th, 7th and 10th or the 12th days (50 or 67.5 mg/kg a day) after the infection inhibited the growth of M. tuberculosis in the spleen tissue, while analogous doses of streptomycin solution had no such an effect. With respect to the lung tissue, the antibacterial effect of the liposome-incorporated streptomycin was not potentiated. When the liposome-incorporated streptomycin was administered 3 times, the life-span of the animals was increased and the loss of the body weight was retarded as compared to the results of an analogous treatment course with the use of streptomycin solution. The acute toxicity of intravenous streptomycin incorporated into liposomes was lower as compared to that of streptomycin solution.