In the last decade renal transplantation has gained considerable development. This is due to the achievements of clinical immunology and refinement of the surgical technique. In spite of all this, the achievements of renal transplantation are variable. This primarily is due to T-lymphocyte mediation, causing hazards for graft rejection. At present, numerous therapeutic agents, blocking the immune response of the organism, are applied. They are most effective when block selectively the activity of the immune cells responsible for immune response. The first synthesized preparation is Orthoclone OKT3 (Muronab-CD3). It is a sterile solution of murine monoclonal antibody to T3 (CD3) antigen in human T-cells and functions as immunosuppressor. The first experimental data on its application have been published in 1975. In 1980 the preparation was applied for the first time for treatment of acute reaction for grafted kidney rejection. The authors set themselves the task to give a brief review of the nature of this preparation, mode of its storage, indications for use, side reactions and their prophylaxis.