The present invention pertains to engineered T-cells, method for their preparation and their use as medicament, particularly for immunotherapy. The engineered T-cells of the invention are characterized in that the expression of beta 2-microglobulin (B2M) and/or class II major histocompatibility complex transactivator (CIITA) is inhibited, e.g., by using rare-cutting endonucleases able to selectively inactivating by DNA cleavage the gene encoding B2M and/or CIITA, or by using nucleic acid molecules which inhibit the expression of B2M and/or CIITA. In order to further render the T-cell non-alloreactive, at least one gene encoding a component of the T-cell receptor is inactivated, e.g., by using a rare-cutting endonucleases able to selectively inactivating by DNA cleavage the gene encoding said TCR component. In addition, expression of immunosuppressive polypeptide can be performed on those modified T-cells in order to prolong the survival of these modified T cells in host organism. Such modified T-cell is particularly suitable for allogeneic transplantations, especially because it reduces both the risk of rejection by the host's immune system and the risk of developing graft versus host disease. The invention opens the way to standard and affordable adoptive immunotherapy strategies using T-Cells for treating cancer, infections and auto-immune diseases.