Abstract: We reported the results of biological and toxicological study, realized on Mitragyna inermis Willd Oktze, one specie of family of Rubiaceae, well known in traditional medicine in Burkina Faso for his intensification potentialities of resistance against multiple pathologies like infectious and parasitic diseases, adynamia, rheumatic and osteoarthritis diseases. So we have formulated hypothesis of stimulation of organism’s defenses for a scientist research. The steeping freeze-dried of the plant’s product has been used for different assays: General acute toxicity estimation on Ico mouse (NMRI Han) by intraperitoneal route and orally administration on rabbit from the value of LD50 obtained with the mouse. Biological study: The kinetic interaction between the plant’s product chemical group and the evolution of biological elements medium of immunity on the rabbit, has been appreciated. The biological elements include white blood cells, red blood cells, lymphocytes, platelets, total proteins, albumin and globulins. The following results have been obtained about the study: A Lethal Dose (LD50) resulted from maceration (acute general toxicity) at the rate of 800 mg kg-1 of corporal weight showing a bit toxic product. An interaction between vegetable’s extract chemical group and biological elements of rabbit which is expressed by: An increasing (13 to 18%) of total proteins from serum; this increasing was notably after 24 h of administration. Albumin decreasing of 10% in comparison with initial rate, indicated haptens action of plant’s extract chemical products. α1, α2, β and γ globulins increasing, respectively 46.8, 14.31 and 26% during the first day of administration of the extract. A lymphocyte increasing of 35% 24 h after administration of the product. This rate is more increased after the second administration; White blood cells are also increasing. These results show an obvious capacity of the plant’s macered extract to stimulate organism natural defenses in relation with antigenous-antibody reaction. This will be an interesting perspective for complementary treatment of pathology like HIV diseases.