Immune-deficient nude mice were inoculated with nude mouse derived Mycobacteriurn leprae by multiple routes （intravenously. subcutaneously at the foot pads and ears）. The results showed that these inoculated animals were capable of producing a great number of Mycobacterium leprae to a level 10（11-12） per gram of tissue. and were detected histopathologically to have heavy leproniatous lesions. The dissemination of the infection was found particularly in sites with lower body temperature.The organisms have a partiality to striated muscles and peripheral nerves. The authors suggest that experimental leprosy in nude mice is a very useful tool for leprosy resarch. especially in countries without armadillos. Compared with the single-route inoculation reported previously. multiple-route inoculation is more available.