This thesis investigates the Quantitative aspect of epidemic phenomena utilizing the analytical method of discrete time systeMs based on the theory of Markov processes. In particular, the pattern on the epidemic character of turberculosis controlled by prophylaxis and BCG vaccinatioll was analyzed by the markovian model of tuberculosis system which is derived according to the ecologic relationship between nine epidemiologic states of individuals. The quantitative aspects of the model were characterized by digital computer simulations.