Lyophilized Bacterial Lysate is an immunostimulating, obtained by mechanical lysis, whose mechanism of action is the increase of the defences of the organism against the micro-organisms responsible for the infections of the high breathing channels and the bronchopulmonary tract. Lyophilized Bacterial Lysate has shown a protective activity in the experimental infections documented by immunoelectrodiffusion, with induction of specific antibodies represented by Ig (Immunoglobulin), stimulation of splenic lymphocytes with formation of “rosette”. Depressive or stimulating effect on the cardiovascular and breathing apparatus are absent. The immunostimulating properties of Lyophilized Bacterial Lysate seem to be induced by: Restoration of the insufficient properties of the T Lymphocytes membranes.